Playing his maiden ATP 1000 final, eighth seed Schwartzman raced out of the blocks to convert two break point opportunities for a 3-0 lead as Djokovic struggled to put a lid on his backhand errors.
An on-and-off drizzle at Foro Italico added to Djokovic's frustration but he still found a way past Schwartzman's serve to draw level at 3-3.
Djokovic's relentless baseline hitting came to the fore when he broke Schwartzman in the 12th game to take the opening set, despite committing 18 unforced errors.
Schwartzman, who outplayed defending champion Rafa Nadal in the quarterfinals, snatched another early break in the second set but this time Djokovic was quick to respond.
The top seed stepped up the intensity to break Schwartzman's serve twice before serving out the match comfortably to seal victory.
"It was a great week, a very challenging week," Djokovic said on court after the match. "I found my best tennis when I needed it most."
"I'm proud that I managed to find the fifth gear when I needed it."
Djokovic's win moves him clear on the list of Masters 1000 titles, one ahead of rival Nadal, and sets him up perfectly next week's rescheduled French Open.
The result also comes as a relief for Djokovic, who was desperate to return to court this week following his U.S. Open disqualification for inadvertently striking a line judge with a ball.
Heading into the French Open, Djokovic has now won 31 of his 32 matches this season, and will be one of the favourites in Paris alongside 12-times winner Nadal and newly-crowned U.S. Open champion Dominic Thiem.