Owings' deal is a Major League contract worth a reported $1 million, and he will report to Spring Training when pitchers and catchers arrive in Peoria, Ariz., on Feb. 19.
"Micah will compete for a spot on our staff," Padres general manager Josh Byrnes said in a release. "He is a proven contributor as a starter and as a reliever. Micah's character and versatility made him a priority for us as we looked to add depth to our pitching staff."
Owings, 29, has a 32-31 record over parts of five Major League seasons with the D-backs and Reds. He has a 4.91 ERA in 132 games, 68 starts.
The Padres envision Owings as someone who could spot start, pitch in long relief and, unlike most other pitchers, potentially give the team something with his bat.
Owings is a career .286 hitter in 203 at-bats with nine home runs and 35 RBIs. He's had seven hits in his last 33 at-bats over the last two seasons.
"He's available to start and relieve, he's acclimated to both and has big league experience," San Diego manager Bud Black said of Owings, who has Minor League options. "I like the natural cut to his fastball. There's a lot to like about him.
"He makes us deeper. And in the event he makes the club, he provides us depth with another guy who is a Major League quality pitcher."
Owings went 8-0 last season in his second stint with the D-backs, who selected him in the third round of the 2005 First-Year Player Draft out of Tulane. He reached the Major Leagues in 2007, going 8-8 with a 4.30 ERA for a team that won the National League West under Byrnes.
Owings was then dealt to the Reds as the player to be named later in September 2008. He went 10-14 with a 5.35 ERA in two seasons in Cincinnati before signing with the D-backs last January.
With the addition of Owings, the Padres have a full 40-man roster.
Elsewhere, Padres center fielder Cameron Maybin has officially switched agents. Maybin is represented by Brian Goldberg, his original agent. Goldberg was the longtime agent for Ken Griffey Jr.