Goodwin tweeted in April that he planned to compete in the long jump. He confirmed that sentiment when speaking to reporters Tuesday.
He said he will use the Olympic process as part of his training during the off-season.
"It's the same mechanics I use in football as in track," Goodwin said.
Goodwin previously competed in the long jump at the 2012 Olympics in London. He placed 10th in the event before his final season at the University of Texas. He went on to be a third-round pick by the Buffalo Bills in the 2013 NFL Draft. Goodwin joined the 49ers in the 2017.
Goodwin attempted to return for the 2016 Summer Games, but came up short in his bid to qualify. Goodwin was suspended by the United States Anti-Doping Agency (USADA) two years ago after failing to reveal his location for potential drug testing. He followed the suspension by saying he quit the sport to focus on football.
He was not subject to discipline under the NFL policy on performance-enhancing substances as a result of the USADA's decision.
Goodwin signed a three-year, $19.25 million contract extension in March 2018.
Goodwin is regarded as one of the fastest players in the NFL. He plans to participate in the Forty Yards of Gold event on June 29 in Sunrise, Fla. The event will consist of 16 players competing in 15 races to determine the NFL's fastest player.
The 5-foot-9, 180-pound pass-catcher had 395 yards and a career-high four touchdowns on 23 catches in 11 games last season for the 49ers. Goodwin had a career-high 962 yards on 56 receptions in 16 starts during his 2017 campaign in San Francisco. He also had two touchdowns and 105 targets in 2017.
"I think we always have a pretty good idea of who Marquise will be and what he can do. The benefit this year is that there are other people to take some pressure off," 49ers coach Kyle Shanahan said of the team's off-season additions.
Olympic trials for track and field begin in June of 2020 in Eugene, Ore.