After two dropped service games cost the Russian the opening set, she recovered well to edge her Canadian opponent in the second.
Careless errors cost Bouchard dearly in the decider, while Sharapova's serve held strong as she reached her third final in as many years with a 4-6 7-5 6-2 win, but the number seven seed believes she can count herself lucky.
"She (Bouchard) played an unbelievable match today," Sharapova said. "Her level was extremely high and I was fortunate to win because she played tremendous tennis.
"Obviously, I would prefer to win in two sets. It was tough losing that first set, but that's not when the match ends and that's why you put in the hard work - to get through those moments."
Sharapova won at Roland Garros in 2012, and is bidding to regain the title after losing last year's final to Serena Williams.
Awaiting her in Saturday's showpiece will be either Simona Halep or Andrea Petkovic, neither of whom have ever made it beyond the last eight of a grand slam, but Sharapova does not believe that inexperience will count against them.
"Sometimes when you play someone who's never been in that situation, they play loose and there's not much you can do," she added. "You just hope they slow down a little bit."