Larkin, 51, will begin as a roving infield instructor for the Reds' Double A team in Pensacola, Fla.
Larkin was an ESPN analyst until this season, freeing him for a position with the team that both sides had discussed previously.
"He said he'd like to but talk about maybe a more of an expanded role," Reds general manager Walt Jocketty told reporters. "We talked about it. When he came to spring training, we kind of worked on it some more. We just finalized something now. He still has a lot of commitments even though he doesn't have TV. At the time when I talked to him, in January, the first time, he was still waiting to hear on some TV stuff. Once that was cleared, he was able to spend a lot more time with us."
Larkin spent all 19 seasons of his MLB career with the Reds, retiring after the 2004 season with 12 All-Star appearances, the 1995 National League MVP award, a World Series championship in 1990, nine Silver Slugger Awards and three Gold Glove Awards. The shortstop hit .295 with 198 home runs, 960 RBIs and an .815 OPS over 2,180 career games.
Larkin was voted into the Hall of Fame in 2012. He managed Brazil in the 2013 World Baseball Classic and also interviewed for the Tampa Bay Rays manager job this offseason.
- Mike Fiammetta