The Reds said Monday the 29-year-old Gomes had signed a one-year, $800,000 major league deal, with a $1.75 club million option for 2011.
General manager Walt Jocketty said the 29-year-old Gomes will compete for the job in left field.
"After I met with [manager Dusty Baker] and the coaches after the season, we put together a list of things we wanted to improve on for this season," Jocketty said. "The last thing on the list we hadn't checked off was a right-handed power hitter. I definitely think Jonny fills that role. There will definitely be a lot of competition for that spot in the outfield."
Gomes lives in the Phoenix area, drove to the Reds' camp and passed a physical on Monday, then signed his deal.
"Walt and Dusty grabbed me and took me in with open arms," Gomes said. "It was exciting to see the young, core guys mature through the season, and then the other guys Walt brought in. From the outside looking in, it's a well-put-together team for this year."
The Reds put right-hander Edinson Volquez on the 60-day disabled list to create room on the roster. Volquez had reconstructive elbow surgery last August and isn't expected back before midseason.
Gomes became a free agent when the Reds declined to offer him a contract at the tender deadline in December.
"We always had interest in bringing him back, but he wanted to test the market and see what was out there,'' Jocketty said. "I think he realized at the end that this was the best place for him. We still needed a power bat in the middle of our lineup, and we wanted to give him an opportunity to improve upon what he did last year.''
Gomes said that Cincinnati was always his "No. 1 stop'' after Jocketty and Baker welcomed him with "open arms'' last year.
"It was definitely a different offseason,'' he said. "It seems like a lot of free agents overplayed their hands, but that definitely wasn't my case at all.
"After the non-tender, the No. 1 thing on my plate was a major league deal. It took all the way to February 22, but it doesn't matter when you sign as long as you get in before camp. Here I am.''
Gomes signed just in time to attend the Reds' first full-squad workout, which is scheduled for Tuesday at the team's new spring training location in Goodyear.
Gomes appeared in 98 games for the Reds last season, batting .267 with 20 homers and 51 runs batted in. He started 33 games in left field, 33 in right and nine as a designated hitter during interleague play.
Gomes has been talking to the Reds about a deal over the winter.
Gomes has 86 homers and a .471 slugging percentage in seven seasons with Tampa Bay and Cincinnati. He's expected to add some power and experience to a young Cincinnati outfield that currently consists of Jay Bruce in right field, Drew Stubbs in center and Chris Dickerson, Laynce Nix and Wladimir Balentien battling with Gomes in left.
Gomes can earn $500,000 in performance bonuses this year: $50,000 each for 250, 300 and 350 plate appearances; $100,000 each for 400 and 450; and $150,000 got 500. If he's sent outright to the minor leagues, his salary would be $100,000.
The 2011 option would carry a $50,000 buyout if he has 200 plate appearances this year. The option price would increase to $100,000 if he has 250 plate appearances, $150,000 for 300 and $200,000 for 350. If the option isn't exercised, Gomes would be given his unconditional release.
If the option is exercised, Gomes could earn $750,000 in performance bonuses in 2011: $50,000 each for 250, 300 and 350 plate appearances; $100,000 each for 400 and 450; and $200,000 each for 500 and 550.
The Cubs had expressed interest in Gomes earlier this offseason, but chose to sign Xavier Nady as a right-handed outfield bat.
Information from ESPN.com senior writer Jerry Crasnick and The Associated Press was used in this report.