Djokovic is 3-0 overall against Monfils.
"He is one of the players who is very unpredictable," Djokovic said. "He can play really, really fast. And with a big serve, he can do a lot of damage to opponents."
The third-ranked Djokovic was dominant from the start and didn't face a single break point en route to the victory over Nadal. Winning 83 percent of first-serve points, Djokovic also had 31 winners.
"I felt so good on the court that all the shots I hit transformed into winners," Djokovic said. "It was perfect, exactly the way I wanted."
Djokovic defeated Nadal for the second consecutive time to improve his overall record to 6-14 against him. He reached his 10th final of the year.
Nadal defeated defending champion Jo-Wilfried Tsonga in the quarterfinals after two difficult three-set matches in the previous rounds.
"I finished this tournament much better than I started," Nadal said. "The confidence will not go away because I lost 6-2, 6-3 to Djokovic."
Djokovic took the first set after claiming four games in a row. He pumped his fist when he broke the second-ranked Nadal at love to lead 4-2 with a backhand winner down the line. He didn't lose a point in the next two games, overwhelming his rival with powerful groundstrokes and subtle drop shots.
Nadal, who lost 14 straight points on his serve and seven consecutive games overall, was broken at love for the third time in a row when Djokovic hit another forehand down the line for a 2-0 lead in the second set.
Djokovic, who defeated top-ranked Roger Federer in the Swiss Indoors final last week, twisted his ankle in the seventh game after firing a crosscourt backhand passing shot. But he held serve and closed out the match with a forehand winner.
Monfils broke in the fifth game before clinching the set when Stepanek sent a backhand wide.
In the second set, Monfils served for the match at 5-4 but Stepanek broke him twice in row behind strong play at the net.
Monfils and Stepanek traded breaks early in the third. Monfils broke in the ninth game when Stepanek missed a volley.
"I found a solution by digging deep in my mental resources," Monfils said. "I gave the proof that I'm a great player."
He knows he'll have to find more inner strength against Djokovic.
"I'm burnt out, but tomorrow it will be a fierce mental battle," Monfils said.
Nadal returned to competition in October after a month off because of a pulled stomach muscle. He reached the semifinals in Beijing, then the final in Shanghai where he lost to Nikolay Davydenko. His last title victory on the tour came in May at the Rome Masters.
Nadal and Djokovic are among eight players who will compete in the ATP World Tour Finals on Nov. 22-29 in London.
Nadal is also expected to play the Davis Cup final when defending champion Spain will host the Czech Republic on Dec. 4-6 in Barcelona.