Osterman went pro in 2007, playing for the Rockford Thunder of the National Pro Fastpitch League (NPF) in 2007 and 2009 before heading to the USSA Pride for five seasons. She initially retired in 2015 after winning four league titles and six All-NPF team honours. Osterman returned to play for the Scrap Yard Dawgs, which became This Is Us Softball to support racial justice in 2020, as she prepared for her Olympic comeback.