Stroman, whose recovery from a torn left calf muscle was almost complete, announced his decision Monday on social media. He was in line to potentially make his season debut for the Mets next week against the Miami Marlins.
"After much consideration and discussion with my family, I have made the difficult decision to opt out of the remainder of the 2020 season," Stroman said. "With all the unknowns and uncertainty due to the pandemic, this is the best decision for me and my family.
"I appreciate the Mets organization for their support and understanding, and look forward to returning to baseball next season."
Stroman, who is scheduled to become a free agent after the 2020 season, becomes the second Mets player to opt out this month. Former All-Star outfielder Yoenis Cespedes left the team Aug. 2.
Stroman's decision came four days after he tossed 85 pitches in his second simulated game and a day before he was set to throw another simulated game.
Mets manager Luis Rojas said he supported Stroman's choice but was surprised.
"He wanted to do another one just to play it safe and see how he felt coming out of it and then come join us," Rojas told reporters Monday. "But, once again, we fully support him."
Stroman will now go on the restricted list, allowing the Mets to clear a spot on their 40-man roster. He was scheduled to earn $4.4 million -- a prorated amount of the one-year, $12 million contract he signed in January -- this season.
Stroman, an All-Star selection in 2019, posted a 4-2 record and 3.77 ERA in 11 starts for the Mets last season.