Martinelli spent thirteen seasons in the American Soccer League and earned three caps with the U.S. national team in 1937.
In 1934, Martinelli began his professional career when he signed with the Pawtucket Rangers of the American Soccer League (ASL).
After playing in the 1935 Challenge Cup final, Martinelli moved to the New York Americans where he won the 1935–1936 league title.
In 1937, Martinelli finally won the Challenge Cup title when the Americans defeated the St. Louis Shamrocks.
[3] While Martinelli was selected for the U.S. squad at the 1934 FIFA World Cup, he did not enter the lone U.S. game, a 7–1 loss to Italy in the first round.