He played in Major League Baseball for the Providence Grays (1881), Philadelphia Athletics (1882), and Baltimore Monumentals (1884).

[2] Sweeney began his professional baseball career with the Athletic Club in 1878.

[2] In 1884, Sweeney played for the Baltimore Monumentals of the Union Association (UA), appearing in 62 games and compiling a 40-21 record with a 2.59 ERA.

[3] In 1885, Sweeney played for the Cleveland Forest Cities in the Western League.

[2][4] As of 1887, Sweeney was with the Beford Club when frequent hemorrhages put his life in danger.