Barnes tucked home a penalty to put the result beyond doubt and move Brighton within three points of the playoff places.
Below, Sports Mole casts its eye over an entertaining game on the South coast.
On target 4
On target 8
Was the result fair?
Just about, yes. Brighton were the better side in the first half but then were so fortunate to not concede two quick goals in a spell of dominance for Leicester in the second. Apart from that 10-minute spell, Brighton were the better side and deservedly got three points.
Oscar Garcia won November's Manager of the Month and he certainly has found a good formula at the moment. His side bounced back brilliantly from Tuesday's defeat to rockbottom Barnsley with an assured performance today.
The Foxes will want to forget about the last five days quickly. They had lost just three times in the previous four months but two quick losses means they are no longer top. Today, deadly attacking duo David Nugent and Jamie Vardy were kept very quiet. Anthony Knockaert was dropped to the bench and Nigel Pearson may regret that decision as he looked dangerous when he came on at half time.
Sports Mole's man of the match
David Lopez: He may have only played 74 minutes, but Lopez's two passes for Brighton's goals in the first half were top quality. He was assured on the ball and ensured that Brighton maintained possession well against good opposition.
Really hard to pick out an obvious gaffe today but we're going to highlight King's miss soon after he had pulled one back.
Robert Madley dished out six bookings but didn't have any contentious decisions to deal with. He booked Marcin Wasilewski very early and could have sent off the Leicester defender for a second tasty tackle. The one and only gripe of a solid refereeing display.
Brighton: Next up for the Seagulls is a 315-mile trip North to visit Middlesbrough next Saturday.
Leicester: Meanwhile, it's a massive game next week for Leicester as they host fellow high-flyers Burnley.