An expectant crowd were treated to a vastly-improved performance compared to their team's form in the buildup to the tournament, which resulted in Russia going into the opening match without a win in seven and as the lowest-ranked team in the competition.
Saudi Arabia were only three places above them, though, and Juan Antonio Pizzi's side looked far more worthy of their lowly ranking as Russia ran riot in the capital.
Yury Gazinskiy gave a sign of things to come when he opened the scoring after 12 minutes, but it was Stanislav Cherchesov's substitutions who made the biggest difference, with Denis Cheryshev scoring twice and Artem Dzyuba also coming off the bench to score one and create another.
Cheryshev's second came in stoppage time before Aleksandr Golovin got in on the act with a 95th-minute free kick, capping off a memorable afternoon in style for the host nation as they set an early benchmark in Group A.
The hosts were roared on by a fervent crowd in Moscow and duly made an energetic start to the match, with Alexander Samedov and Alan Dzagoev both failing to make the most of half-chances courtesy of some last-ditch Saudi defending.
However, the latter opportunity created the corner which led to the opening goal of the tournament, and it came from an unlikely source as Gazinskiy scored his first goal for Russia to send the Luzhniki Stadium wild after only 12 minutes.
The initial delivery came to nothing, but Russia kept it alive and Golovin's delivery was met by Gazinskiy, who cushioned his header back across goal and into the far corner.
Russia were quickly on the front foot again and almost doubled their advantage just three minutes later when Mario Fernandes pulled the ball back for Dzagoev, whose effort struck a combination of Fyodor Smolov and Mohammed Al-Burayk before being clawed away from goal by Abdullah Al-Maiouf.
A second goal looked inevitable for Cherchesov's side, but it was Saudi Arabia who almost got it against the run of play when Yasir Al-Shahrani's cross was put just past the Russian goal by Ilya Kutepov at the end of a quick counter-attack.
Russia were on the break themselves from the resulting corner, although that came to an abrupt end when Dzagoev pulled up with a hamstring injury which spelled the end of his match and possibly the end of his tournament.
Dzagoev's departure had an immediate impact on Russia as their control over the game began to wane, but replacement Cheryshev ultimately proved to be one of the heroes, and he provided the second goal just two minutes before half time.
The Villarreal midfielder was on the end of another slick counter from the hosts, latching on to Roman Zobnin's slightly underhit pass before skilfully dinking the ball past two sliding defenders and blasting his finish into the roof of the net.
In doing so, Cheryshev created a small slice of history by becoming the first ever substitute to score in the opening match of a World Cup, but more importantly it put Russia firmly back in the driving seat going into the second half.
Little changed immediately after the interval either, with Russia creating the first sight of goal when Samedov let fly with a powerful drive from range, only to see it fly over the crossbar.
Saudi Arabia did begin to step things up approaching the hour mark when Mohammad Al-Sahlawi and Taisir Al-Jassim both failed to connect with a teasing cross into the box, before Salman Al-Faraj failed to make the most of a header from inside the area.
It was only a very brief revival from the Green Falcons, though, and Russia were soon back on the front foot with Cheryshev sending a header into the arms of the keeper before Al-Maiouf was fortunate to see his parry from a low Zobnin drive avoid the red shirts in attendance.
Russia's final change came with 20 minutes remaining, and it took just 89 seconds for Dzyuba to make his impact off the bench when he peeled off his man all too easily to guide Golovin's cross into the bottom corner.
A well-struck drive from Salem Al-Dawsari almost provided a quick consolation for Saudi Arabia, but his effort flew wide of the target and it looked as though the game was drifting out into a comfortable win for the hosts during the closing stages.
However, there was one final flurry of quality from Russia as they added two more goals to a highlight reel already longer than many of the team's more pessimistic fans may have expected from the entire tournament.
Cheryshev further alleviated concerns over the severity of Dzagoev's injury with his second of the match in the first minute of stoppage time, collecting Dzyuba's knockdown before impudently firing the ball into the top corner with the outside of his boot.
Cheryshev's hopes of having sole claim to the two best goals of the game were challenged with the final meaningful kick of the match, though, as Golovin curled a pinpoint free kick past the keeper to cap off the rout in memorable fashion.
Russia's victory is the second-biggest by a host nation in their opening match in World Cup history - after only a 7-1 win for Italy in 1934 - putting them in pole position at the top of Group A ahead of matches against Egypt in St Petersburg and Uruguay in Samara.
Meanwhile, Saudi Arabia's hopes of making it into the knockout rounds look even bleaker now as their record of never have won their opening World Cup game continued, leaving them facing matches against Uruguay and Egypt on a four-game losing streak.
RUSSIA (4-2-3-1): Akinfeev; Fernandes, Kutepov, Ignashevich, Zhirkov; Gazinskiy, Zobnin; Samedov (Kuzyaev 64'), Dzagoev (Cheryshev 24'), Golovin; Smolov (Dzyuba 70')
SAUDI ARABIA (4-1-4-1): Al-Maiouf; Al-Burayk, Osama Hawsawi, Omar Hawsawi, Al-Shahrani; Otayf (Al-Muwallad 64'); Al-Shehri (Babhir 74'), Al-Jassim, Al-Faraj, Al-Dawsari; Al-Sahlawi (Aseri 85')