The Pole, a four-times champion who is now on a 22-match winning run in Paris having won the last three titles, is looking to become the first female player to win four straight French Open crowns in the professional era since 1968.
For four-times Grand Slam champion Naomi Osaka it was a disappointing opener with an error-ridden performance that ended in defeat by Spain's Paula Badosa 6-7 (1-7) 6-1 6-4.
Swiatek had arrived more than 10 days before the tournament to get sufficient training on the clay courts and she said it has so far paid off.
"It was the first time we had this situation (of arriving early)," Swiatek said in a post-match interview. "But I liked it. I knew I am going to have the best courts to practice on."
Swiatek, unusually without a title on the tour this season, needed time to find her footing, with the Slovak initially offering greater resistance than in her 6-0 6-2 loss to the Pole at the Australian Open in January.
Sramkova held serve until Swiatek broke her to go 4-3 up before bagging the first set.
The 28-year-old world No.42 broke Swiatek at the start of the second to open up a 2-0 lead but her opponent quickly reined her in with two breaks of her own, winning six of the next seven games to wrap up victory.
Swiatek next faces Britain's Emma Raducanu, who had to battle for more than 2.5 hours before securing a 7-5 4-6 6-3 win over China's Wang Xinyu.
The former US Open champion, who has slipped down to 41st in the world, had to have her blood pressure checked during the first set but came back to win the match, helped also by the Chinese's staggering 54 unforced errors.
Osaka, sporting a cherry blossom-themed outfit, complete with matching nails, had to work hard to snatch a first set from Badosa but the tables were turned with the 10th seed breaking her twice to race through the second set 6-1.
The Japanese former world No.1, who took a medical time out, ultimately paid the price for a slew of unforced errors - at 54, twice as many as Badosa.
Emma Navarro, the ninth-seeded American who reached the US Open semi-finals last September, bowed out quickly in Paris, eliminated 6-0 6-1 in just 57 minutes by Jessica Bouzas Maneiro of Spain.
