Ausmus, 44, has never managed in either the minor or major leagues, but Tigers General Manager Dave Dombrowski said he was confident Ausmus can do the job.
"This guy was born to manage," he said.
Ausmus has served as a special assistant for the San Diego Padres since wrapping up an 18-year playing career in 2010, during which he played twice for the Tigers.
The three-game Gold Glove winner also played for San Diego, Houston and the Los Angeles Dodgers.
Leyland, who retired last week, took Detroit to four playoff appearances and two American League pennants in eight years.
The Tigers won the AL Central with a 93-69 record before falling to eventual World Series champions Boston in this year's AL Championship Series.