The Ukrainian, who returned to action last month after more than a year away, swept past Russian Anna Blinkova (24), 6-2, 6-3.
Blinkova, ranked 66, could find no way past an aggressive and determined Svitolina, who reclaimed the Strasbourg title she won in 2020.
The Ukrainian, who fell to 508th in the world but benefits from a protected ranking, broke serve three times in the first set which she sealed with a ace in just over half an hour.
Svitolina raced to a 3-0 lead in the second set and was 4-1 up before Blinkova showed signs of a fightback, saving three match points at 5-3, before falling after one-hour 32minutes as the Ukrainian won her first title since Chicago two years ago.
The two players did not shake hands at the end, simply giving each other a sign with their rackets.
Svitolina resumed competition in early April in Charleston. Before that she had not played since the Miami tournament in March 2022.
The native of Odessa, who finished in the top 20 seven seasons in a row, had put her career on hold, saying she was "mentally exhausted" and distressed by the war that Russia is waging on her country.
Wife of French tennis player Gael Monfils, Svitolina had her first child last October.
At Roland-Garros, where she has never gone past the quarter-finals, she will face Italian Martina Trevisan, 29, a semi-finalist last year, in the first round next week.
Blinkova will play Belgian Ysaline Bonaventure in the first round.
