The victory extended the Brit's run to six straight ATP Tour events with at least one win, his semifinal showing at Sydney in January still his best result of the season.
Krejcikova won just her fifth major tournament as a singles player by beating 31st-seeded Anastasia Pavlyuchenkova 6-1, 2-6, 6-4 in the final at Roland Garros.
The four-time major champion and No. 2-ranked player was fined $15,000 when she didn't speak to reporters after her first-round victory at Roland Garros on Sunday.
"Happy to let you know that I will play Geneva and Paris," Federer tweeted, DPA reports. "Until then, I will use the time to train. Can't wait to play in Switzerland again."