In 1934, Heilman was hired by WXYZ to handle the play-by-play responsibility on broadcasts of Detroit Tigers games for the Michigan Radio Network. At the start of the 1934 season, he was paired with Harold True, but became a solo broadcaster by the end of the season and thereafter. During the Tigers' 1935 championship season, Heilmann broadcast all home games for the Tigers, while out-of-town games were relayed by telegraph with play-by-play being read by Bob Longstreet from the WXYZ studio in the Maccabees Building. In the fall of 1934, Heilmann also began broadcasting a football highlights show on Saturday evenings on the WXYZ and the Michigan Radio Network. In 1936, he also broadcast out-of-town Tigers games on CKLW radio. He also began broadcasting a sports interview show on WXYZ in 1936. In 1937, Heilmann further expanded his radio responsibilities with a daily recap of the day's baseball games, broadcast at 5:30 p.m. on WXYZ. In 1938, he continued his broadcasts of Tigers home and out-of-town games on WXYZ, and added a 12:45 p.m. interview show with the fan on the street, broadcast Monday through Saturday on WXYZ.