World number three Djokovic, who had outclassed Rafael Nadal in the semi-finals and had dropped only one set en route to the final, had to dig deep to win his second title in as many weeks.
Outplayed at first, Monfils, seeded 15th, thrilled a partisan 14,000 crowd packing the Bercy hall by fighting back to win the second set and recovering from 4-1 down to level the decisive set before losing it 7-3 in a tiebreak.
Djokovic, who beat world number one Roger Federer in the Basel final week, showed signs of nerves at times and had to wait for Monfils to double fault on the first match point to seal victory after two hours 43 minutes.
“It was incredibly tough,” Djokovic said after winning his fifth title this year but his first in 2009 in the showcase Masters 1000 Series.
“Gael is very unpredictable. He was hitting the ball well and he’s got a strong serve. At first I played unbelievable but then he started coming back, with the crowd on his side.”
The 22-year-old Serb has won 76 matches this year, more than any other player, although disappointing results at major events stopped him from getting anywhere near the number one spot.
London favourite
His current form suggests, however, that he will be the favourite at the season-ending Nov. 22-29 World Tour Finals in London and could give Federer and Nadal a run for their money in 2010.
Relying on his devastating forehand and hardly making an error, Djokovic wrapped up the first set in just 30 minutes.
The second set’s script was similar at first, another unforced error from Monfils handing Djokovic a 2-0 lead, and a crushing win looked on the cards but the Serb then dropped his guard, enabling his opponent to find his way back into the match.