"After careful consideration and discussion with my family, I have decided to opt out of the remainder of the 2020 season," Cain said in a statement obtained by Adam McCalvy of MLB.com. "With all of the uncertainty and unknowns surrounding our game at this time, I feel that this is the best decision for me, my wife, and our three kids.
"The Brewers organization was very understanding and supportive of my decision, and I thank them for that. I wish all of my great teammates the best of luck this season and look forward to getting back on the field in 2021."
Brewers general manager David Stearns stated: "We fully support Lorenzo's decision and will miss his talents on the field and leadership in the clubhouse."
The veteran outfielder will walk away from $5.92 million - the prorated portion of his 2020 salary - after opting out, according to Tom Haudricourt of the Milwaukee Journal Sentinel.
Cain's decision comes after the Brewers had two games postponed against the St. Louis Cardinals. The Cardinals reportedly had six people on their traveling party test positive for COVID-19.
The 34-year-old joins a growing list of players who have opted out, including Los Angeles Dodgers left-hander David Price, San Francisco Giants catcher Buster Posey, and Colorado Rockies outfielder Ian Desmond.
Cain is a two-time All-Star and won a NL Gold Glove in 2019.