Mora played 13 seasons in the big leagues, 10 of them with the Baltimore Orioles. He began last year with the Arizona Diamondbacks, was released on July 1 while hitting .228 with no home runs and did not play again in the majors.
"It's a very difficult decision because this has been my life, but it's time to do it," Mora said Thursday at a news conference in Valencia, Venezuela.
"I've been in this for many years and it's time to dedicate myself to my family," he said.
Mora and his wife had quintuplets in 2001.
Mora was a career .277 hitter with 171 home runs and 754 RBIs with Baltimore, Colorado, Arizona and the New York Mets. His best season was 2004, when he hit .340 with 27 homers and 104 RBIs for the Orioles and led the American League with a .419 on-base percentage.
Versatile with his glove, he played every position in the majors except pitcher and catcher.
After a solid season for the Rockies in 2010, he signed a US$2 million contract with Arizona for the 2011 season. But Mora injured his neck in a car accident during spring training and later missed time while on the bereavement list. Late in June, the Diamondbacks said they planned to cut him.
Born in Venezuela, Mora began his pro career in 1992. He was in the minors until 1999, when he made his big league debut and became a post-season sparkplug for the New York Mets. That was the only year Mora reached the playoffs.
"I've had a beautiful career that I will always remember," he said.