The 2009 Australian Open champions rallied from a 5-3 deficit to force a tiebreaker in the first set before cruising in the second.
Jans-Ignacik and Gonzalez were playing their first Grand Slam final.
Meanwhile, American twins Bob and Mike Bryan moved one victory away from their 12th Grand Slam doubles title, beating Aisam-ul-haq Qureshi of Pakistan and Jean-Julien Rojer of the Netherlands 6-3, 7-6 (6) Thursday to reach the French Open final.
"Expectations are a lot higher," Bob Bryan said. "I remember when we made the quarters in '02. ... 'Great tournament, guys. Awesome job.' And that's how we felt in '02. Now if we don't come in and win, we're taking swings at each other back at the hotel."
In women's doubles, Maria Kirilenko and Nadia Petrova defeated defending champions Andrea Hlavackova and Lucie Hradecka 4-6, 7-5, 7-5 in a semifinal that was suspended because of darkness Wednesday, tied at one set apiece.
Errani became the first player since Kim Clijsters in 2003 to reach the final both in singles and doubles at Roland Garros.
She beat U.S. Open champion Samantha Stosur 7-5, 1-6, 6-3 in the singles semifinals on Thursday.