Schmiedlova claimed the first set 6-0. Osaka held a 3-0 lead on the Slovakian in the second set, before needing to break Schmiedlova's serve twice to remain in contention. Osaka won the second set with a tie break 7-6 (4). She dominated the third set 6-1 to advance to the second round.
Osaka had 10 aces and had 38 unforced errors in the 1:54 match. Schmiedlova is No. 90 in the Women's Tennis Association's world rankings.
She will face former world No. 1 Victoria Azarenka in the second round on Thursday at Roland Garros. She is looking to win a third consecutive Grand Slam title. She won the U.S. Open before winning the Australian Open final in January in Melbourne.
American Madison Keys also won her first-round match, beating Evgeniya Rodina in straight sets. Monica Puig also beat Kirsten Flipkens in straight sets in her first-round match.
Azarenka beat Jelena Ostapenko to advance to her second round matchup against Osaka.