Svitolina has been ranked as high as No. 3 and is currently No.1081, because she was off the tour for a little more than a year. She and her husband, fellow player Gael Monfils, became parents in October, when their daughter, Skaï, was born.
The first-round match on green clay lasted two hours, 46 minutes and was filled with momentum swings.
The previous time Svitolina competed at a tournament, at the Miami Open in March 2022, she was ranked No. 20. She received a wild-card invitation to get into the main draw in Charleston.
The 28-year-old from Ukraine entered Monday with a 6-1 head-to-head record against Putintseva, winning their past six matches in a row.
Svitolina reached the semi-finals at Wimbledon and the US Open in 2019 and won the season-ending WTA Finals the year before.
"It's very nice to have her back. She's always been super nice and an inspiration for me, because she was a warrior on court, a fighter, and I love these kind of players. It's even more inspirational seeing her come back as a mom," said Paula Badosa, who is seeded 12th in Charleston.
"I'm very happy for her and I hope soon she's back where she belongs."
In other Day 1 matches, 17-year-old Linda Fruhvirtova beat Jil Teichmann 6-2 3-6 6-2, Anna Kalinskaya defeated Anhelina Kalinina 7-6 (7-6) 6-4, qualifier Katherine Sebov got past Lauren Davis 4-6 6-1 6-2, and Anna Blinkova eliminated Anna Bondar 7-6 (9-7) 6-2 to set up a second-round matchup against top-seeded Jessica Pegula.