Ferrari's Fernando Alonso took second, while Hamilton was able to hold on for third.
Read how all the action unfolded below:
12.32pmGood afternoon. It's just under half an hour until lights out a Spa-Francorchamps, where Lewis Hamilton will be going for back-to-back race wins. If you need a reminder of the grid for today's race, check out our qualifying report.
12.34pmYesterday, the weather played a big part in qualifying. At the moment, it's dry at the track, but there are some threatening looking clouds hovering around, so a dry race isn't a certainty this afternoon.
12.37pmFor a time, it looked like Paul di Resta would secure his first F1 pole position, but drying track conditions saw the Scot slip down to fifth, which equals his best qualifying performance of the season. Jenson Button also had his best Saturday of the season so far, joining Di Resta on row three.
12.41pmLewis Hamilton's car has just been pushed onto the grid. It's a slightly later than usual arrival, but team principal Ross Brawn confirms that the Brit put in a few extra laps on the way to the grid to get a feel for the track conditions.
12.44pmTyre strategy will be key for those near the front of the grid this afternoon. Usually, drivers that reach Q3 start on the tyres that they set their fastest qualifying lap on, but with yesterday's laps being completed on intermediate tyres, the top 10 will have a free choice of slicks.
12.48pmOne driver everyone will be watching at the start will be Lotus' Romain Grosjean. The Frenchman caused a huge crash at La Source on the opening lap last year, resulting in him being banned from the Italian Grand Prix two weeks later. He'll start the race from seventh, but will be looking to move up the order, according to this tweet from the team:
12.55pmWith not long until the race gets underway, it's time for a quick prediction. It's always difficult to guess how a race with changeable conditions is going to go, but the Mercedes pair both showed that the conditions suited them yesterday. If he can keep Vettel behind him during the dry, the rain should give Lewis Hamilton a race victory.
12.58pmIt looks like the majority of the drivers at the front of the grid are starting on the softer slick compound. The only ones using the harder tyres are the Marussia, Ricciardo and Gutierrez.
1pmFORMATION LAP! Lewis Hamilton leads the cars off the grid for the formation lap.
1.03pmHamilton is weaving around as he tries to get heat into his tyres on the formation lap. The track is mainly dry, but there are a couple of damp patches around.
LAP 1LIGHTS OUT! Hamilton gets a great start, quickly pulling away from Vettel, who immediately faces pressure from Rosberg.
LAP 1Vettel manages to get into Hamilton's slip stream out of the exit of Eau Rouge and eases past the Mercedes for the race lead. Button has also gained places from the start, while Mark Webber struggled to get off the grid, and has dropped down the field.
LAP 2Alonso is battling with Button for fourth place, but the McLaren is faster in a straight line, allowing him to keep the Spaniard behind. Vettel has already opened up a 2.6 second lead.
LAP 3Vettel is showing impressive pace at the front of the race, but his engineer instructs him to look after his tyres. Meanwhile, Massa has dropped back to 12, reporting that his KERS is not working. That's going to cause problems for the Brazilian as his teammate is showing the Ferrari has the pace to be running much higher up the field.
LAP 4Alonso is flying! He manages to pass Button with the aid of DRS to move up to fourth. Next up the Ferrari is Nico Rosberg.
LAP 6Alonso has already closed the gap to Rosberg, and gets the job done using DRS again. He's gained a place a lap so far! However, second-placed Hamilton is almost three second up the road.
LAP 7Further down the field, the Marussia duo, who both made it through to Q2 yesterday have slipped back to 21st and 22nd. However, Caterham's Giedo van der Garde is just a couple of second behind Valterri Bottas of Williams in 19th.
LAP 9Perez moves up to 10th with a bold overtake on Grosjean heading into Les Combes. The Frenchman tries to maintain the racing line, but runs wide, allowing Massa past as well.
LAP 10Perez is under investigation for forcing Grosjean off the track with the overtake, that could see the Mexican handed a drive through penalty. Meanwhile, Massa and Hulkenberg both come in for fresh tyres.
LAP 11Kimi Raikkonen has been asked by his team to try to manage his brake temperatures. His front left disc has been letting some dust out over the last couple of laps. Di Resta also comes into the pits for new tyres.
LAP 12OUT! Charles Pic has been forced to retire his Caterham with a technical problem.
LAP 13PENALTY! Perez has been handed a drive-through penalty for forcing Grosjean off the track. Meanwhile, Hamilton comes in for new tyres from second place, coming back onto the track behind Grosjean.
LAP 13TOP 10! 1. Vettel, 2. Alonso, 3. Rosberg, 4. Webber, 5. Button, 6. Raikkonen, 7. Perez, 8. Grosjean, 9 Hamilton, 10. Ricciardo
LAP 14Hamilton manages to get past Grosjean, but the Lotus still has plenty of grip, and manages to get the place back one corner later. Alonso, Rosberg and Webber all pit.
LAP 15Perez has completed his drive-through, but says over his radio: "I did nothing wrong". The race leader also comes into the pits, and it's a typically smooth change of tyres by the Red Bull mechanics.
LAP 16Alonso and Hamilton are side by side heading down the Kemmel Straight, but the Ferrari driver gets the better of the Brit under braking and manages to maintain the racing line into Les Combes, while Vettel, having dropped down the field to get new tyres, quickly sweeps past Button to regain the lead.
LAP 17Alonso moves up to second, passing Button just before the pit entrance, but the McLaren driver dives into the pits for fresh tyres. He's now used both tyre compounds, so this might be his only pit stop if he can make his tyres last.
LAP 18Di Resta, Perez and Sutil head into Eau Rouge three-a-breast, and it's the German who comes off best, forcing his way ahead of the McLaren driver, while his teammate drops down to 13th.
LAP 20Alonso tries to close the gap to Vettel, but the race leader responds, extending his lead by another 0.2 seconds. He's now almost eight second ahead of the Spaniard. There are still a few dark clouds hanging around, but a couple of teams have said that they're not expecting a shower until after the race.
LAP 21Caterham have confirmed that Pic's retirement earlier in the race was due to an oil leak, and that they brought him in to prevent engine damage. Back on track, Grosjean is still yet to pit, he's definitely going for a one-stop strategy this afternoon.
LAP 23Grosjean finally comes in to change to the hard tyres. Ahead of the race, Pirelli said that a one-stop strategy would work, but the F1 tyre supplier recommended making the change on lap 19, so the Lotus driver managed to save his medium-compounds well.
LAP 24Raikkonen is lining up a move past Massa for seventh, but he can't match the Ferrari's tight line through Eau Rouge, leaving him too much to do down the Kemmel Straight. Massa has recovered well since reporting a KERS issue early in the race. A couple of corners later, the Finn appears to have dropped back, but he quickly closes in again to resume the battle.
LAP 25TOP 10! 1.Vettel, 2. Alonso, 3. Hamilton, 4. Rosberg, 5. Webber, 6. Button, 7. Massa, 8. Raikkonen, 9. Sutil, 10. Di Resta.
LAP 26OUT! Raikkonen tries another move to get past Massa heading into the chicane, but his brakes are struggling, and he goes straight on. The 2007 world champion manages to make the pit entrance, and his mechanics quickly push the car back into the garage. That's Raikkonen's first retirement since Germany 2009.
LAP 28CRASH! Maldonado, Gutierrez and the Force India's head into Blanchimont side by side. The Mexican forces Maldonado wide. The Venezuelan initially hits Sutil before collecting Di Resta's car.
LAP 29OUT! Di Resta's car comes to rest in the barriers and he quickly gets out of the car. That's his race over. Maldonado manages to get his car back to the pits for a fresh front wing.
LAP 30Webber, who had been running in second, makes his second pit stop, heading back onto the medium compound tyre, rejoining the race in sixth. Meanwhile, the stewards confirm that they are investigating the collision between Di Resta, Sutil and Maldonado.
LAP 31Vettel also comes in for tyres, and manages to get back out ahead of Alonso, although the Spaniard has just set the fastest lap of the race so far.
LAP 32Vettel is warned that his tyres have to last him until the end of the race, but he's also told to increase the gap to Alonso as there may be a shower coming. If the rain does hit before the end of the race, it will be a scramble to get back to the pits for intermediates or wet tyres.
LAP 34Button, who has only pitted once, has just been told that McLaren are switching him back to "Plan A". He agrees, telling his enginner, "I'm up for that". I think it's safe to assume that Plan A is a one-stop. Button is currently third, with those behind him on fresher tyres. He'll have to defend well if he's to hold onto a podium place.
LAP 34TOP 10 1. Vettel, 2. Alonso, 3. Button, 4. Hamilton, 5. Rosber, 6. Webber, 7. Grosjean, 8. Massa, 9. Ricciardo, 10. Perez
LAP 35PENALTY! Max Chilton has been given a drive-though penalty for ignoring blue flags. The Marussia driver is at the back of the field.
LAP 35It appears that Button's Plan A is not a one-stop strategy, as the McLaren comes into the pitlane for a fresh set of hard tyres.
LAP 37Vettel, Alonso and Hamilton currently occupy the top three, but Rosberg is just a couple of second behind his Mercedes teammate, and it battling to hold on to fourth with Webber less than half a second behind.
LAP 38PENALTY! Pastor Maldonado has been given a 10-second stop and go penalty for causing the collision with Di Resta and Sutil. The Williams driver isn't running in the points at the moment, but that ends any chance he had of finishing in the top 10.
LAP 39Webber is still looking for a way past Rosberg, who has upped his pace in order to keep the Australian behind him. As a result, Rosberg is getting closer to his teammate, who is not just over two seconds up the road. Vettel looks comfortable with a lead of over 11 seconds from Alonso.
LAP 40PENALTY! Maldonado has come in for his penalty and rejoins in 17th. Meanwhile Esteban Gutierrez is the latest driver to be handed a penalty. He's been given a drive-through for gaining an advantage by leaving the track. It's been a busy afternoon for the stewards.
LAP 41With just three laps left to go, it looks like the rain isn't going to arrive before the end of the race. Ricciardo lines up a move on Perez as the pair come out of Eau Rouge, and the Toro Rosso heads past to move into 10th. The Australian has driven well this afternoon, having started from 19th.
LAP 42TOP 10! 1. Vettel, 2. Alonso, 3. Hamilton, 4. Rosber, 5. Webber, 6. Button, 7. Massa, 8. Grosjean, 9. Sutil, 10. Ricciardo.
LAP 43Vettel is told to drive within himself as he guides his car around the final two laps of the Belgian Grand Prix, He has a 17-second lead but was still pushing hard enough to set a new fastest lap last time around.
LAP 44Vettel begins his final lap of the race.
LAP 44SEBASTIAN VETTEL WINS THE BELGIAN GRAND PRIX!
2.29pmThe reigning world champion took the lead on the exit of Eau Rouge on the opening lap and never came under threat, it's a typical Vettel race win. Alonso brings the Ferrari home for second, while Hamilton seals third.
2.31pmTOP 10 & POINTS: 1. Vettel (25pts), 2. Alonso (18pts), 3. Hamilton (15pts), 4. Rosberg (12pts), 5. Webber (10pts), 6. Button (8pts), 7. Massa (6pts), 8. Grosjean (4pts), 9. Sutil (2pts), 10. Ricciardo (1pt)
2.34pmThe result sees Vettel extend his lead at the top of the drivers standings to 46 points, while Alonso moves above Raikkonen into second.
2.36pmWell that's all from Spa this afternoon, but stick around for reaction to this afternoon's race, and join us again is two weeks for coverage of the Italian Grand Prix from Monza. Until then, thanks for joining me this afternoon, goodbye.