Lutz, 25, started the season at Double-A Pensacola and batted .360 with six home runs and 16 RBIs in 23 games before a May 17 promotion to Triple-A. He was batting .200 in five games at Louisville.
"He's got power. He's got speed. He's got good, youthful aggression, and he brings all the right type of energy we like to the ballpark," Reds manager Bryan Price said.
Lutz played in 34 games for the Reds in his first big league action last season, from April 29-June 24, and batted .241 with one homer and eight RBIs. Naturally, he was happy to be back.
"It's not like I expected to be here; I've got to earn my way on here, and now it's the time to put up the numbers so that hopefully I can stay here," said Lutz, the first German-developed player in the Majors.
Defensively, Lutz played only in the outfield and only had two games this season at first base in the Minors.
"In the Minor Leagues, I'd always take ground balls, just to stay fresh," Lutz said.
The Reds need depth at first base while Joey Votto is on the disabled list with a distal quadriceps strain, and Lutz can provide that and a left-handed bat off the bench. However, Price expected backup catcher Brayan Pena to get a bulk of the starts at first base. But Pena will be catching Monday when Johnny Cueto starts at Los Angeles, leaving Lutz to face Dodgers lefty Hyun-Jin Ryu.
"It doesn't scare me for Donald," Price said. "He gives you good at-bats against left-handed and right-handed pitchers. If I can avoid having him sit for a long period of time, I'd like to be able to do that. [But], when you have Brayan's bat in the lineup over there at first, we kind of know what we've got there. It's a situation where I want to give him playing time. I just don't know how much I can. We'll just see how it unfolds."
Soto, who made the big league club out of Spring Training, struggled at the plate while playing sparingly. A first baseman, he batted .107 in 19 games and was used for two games to fill in for the injured Votto.