The midfielder scored one and created two for Jamie Vardy as the Foxes overcame the battling Hornets at the King Power Stadium
Ademola Lookman added a fourth in the second half to seal the game and end Watford’s hopes of comeback.
Josh King’s penalty briefly levelled in the first half and, while Emmanuel Dennis made it 3-2 after the break, Claudio Ranieri’s Hornets slipped to defeat on the Italian’s first return to the King Power Stadium as a manager since being sacked by Leicester in 2017.
Leicester now sit five points adrift of the top four, with Maddison having scored in successive games for the first time since January.
“It was great, you can see his quality, he was a real inspiration for us,” said Rodgers, following the victory in blizzard conditions.
“We always have a point to prove every single day. For him it was looking at his game, he knows this is a game and a level where you are always looking to prove yourself. You can never be calm with that, you always have to be intense.
“You are seeing the work, not just with him but the confidence returning to the team. It’s not about the one player, it’s about the team but he was excellent today.
“It was a really good performance, we were a real threat going forward. We were playing against a dangerous team, they scored five at Everton, four in their last game against Manchester United. It’s an important three points.”
Maddison cashed in on a gift from William Ekong when the defender ducked under Jonny Evans’ pass to allow the midfielder, who had snuck in behind him, to score the opener.
After Cucho Hernandez’s deflected effort hit the post King made it 1-1 in the 30th minute, netting from the spot after Wilfred Ndidi tripped Dennis.
Yet Vardy restored Leicester’s lead four minutes later, clipping the ball over Daniel Bachmann after Maddison’s excellent pass, and celebrated in front of his former manager Ranieri.
The ex-England international then added a third eight minutes later, glancing in Maddison’s corner for his ninth goal of the season to put Leicester in control.
Dennis made it 3-2 in the 61st minute when he robbed Timothy Castagne and coolly beat Kasper Schmeichel but Lookman wrapped up the game soon after, tapping in Harvey Barnes’ cross.
Defeat kept Watford 16th, four points above the bottom three but Ranieri, who was serenaded by the Leicester fans having taken them to the title in 2016, remained upbeat.
He said: “The reception was fantastic, I want to say thank you to all the fans, Leicester and Watford fans. They came here on this very difficult day and I want to say thank you because I hope they are proud of us.
“We fought til the end. We created more chances than Leicester but they scored and we didn’t. I am positive because it’s important the team try to create chances.
“We conceded four goals so we can do much better but they won the match because they were more aggressive and more determined than us.
“It was Christmas Day conditions. It wasn’t the pitch, we lost because we made mistakes and Leicester scored the chances they had.”