The eight-time world champion completed the 18-stage race in 4 hours, 32 minutes, 39.9 seconds. Daniel Sordo of Spain took second place, 28.6 seconds ahead of Petter Solberg of Norway.
Loeb went into the final day with a lead of 2 minutes, 41.6 seconds over Sordo and looked to secure the maximum number of points by winning the last stage.
The Citroen driver finished the power stage 1.2 seconds ahead of teammate Mikko Hirvonen of Finland to earn three bonus points and lead Mini driver Sordo by ten points in the standings.
"It's always a great moment to start the season like this, especially in front of so many fans," Loeb said. "Full points in the first race is incredible and for sure it's the perfect start (to my title defence). But Monte-Carlo is my rally and for the others we will have to see."
Loeb won the Monte Carlo Rally for the sixth time to clinch his 68th career victory.
The drivers next compete at the Swedish Rally in Karlstad from Feb. 9-12.