"He certainly is comfortable hitting in this park," manager Joe Torre said after the Dodgers lost 5-4.
Ramirez also singled, stole second and scored on Garret Anderson's single in the second.
Ramirez, traded from the Red Sox to the Dodgers in July 2008, was serenaded with a mix of cheers and boos as he rounded the bases. It was Ramirez's eighth home run this season and No. 554 of his career.
The enigmatic Ramirez played for the Red Sox from 2001-08, helping them to a pair of championships. He was the 2004 World Series MVP.
Ramirez went 1 for 5 with two strikeouts Friday night in his first game back in Boston, a 10-6 win by the Red Sox.
Information from The Associated Press contributed to this report.