Last season with the Indians, Choo batted .283 with 16 home runs, 67 RBIs, 21 steals and a .373 on-base percentage. He earned $4.9 million in 2012 and was in his third and final year of arbitration-eligibility.
Cincinnati acquired Choo in a three-team, nine-player trade that also brought in utility player Jason Donald while sending center fielder Drew Stubbs to Cleveland and shortstop Didi Gregorius to Arizona.
Despite only 10 big league games at the position and none since 2009, Choo is expected to replace Stubbs in center field this season after being a right fielder most of his career.
The Reds are willing to take that gamble because they value Choo's ability as a leadoff hitter. In 99 games in the top spot for Cleveland last season, he batted .310 and had a .389 on-base percentage.
Choo, who can become a free agent at the end of the 2013 season, is represented by agent Scott Boras, and he is expected to be a one-and-done player in Cincinnati.
The Reds are grooming top Minor League prospect Billy Hamilton to be their leadoff hitter and center fielder for 2014, but they are hoping that Choo's skills can improve the club's chances of repeating as National League Central champions.
The 33-year-old Hensley, a seven-year Major League veteran, has previously pitched for the Padres, Marlins and Giants. Last season for San Francisco, the right-hander was 4-5 with a 4.62 ERA in 60 games.
The Reds' spring roster now stands at 58 players.
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.