A third baseman, Steinfeldt played in Major League Baseball for the Cincinnati Reds, Chicago Cubs, and Boston Rustlers.

Steinfeldt was the starting third baseman for the Cubs in the final game of the 1908 World Series, the team's last championship until their victory in 2016.

The next year, he played for the Galveston Sandcrabs and Fort Worth Panthers of the Class C Texas Association.

Debuting in the major leagues for the Reds in 1898, he filled in for Bid McPhee, Tommy Corcoran, and Charlie Irwin as a utility infielder.

[2] On October 24, 1905, the Reds traded Steinfeldt, with Jimmy Sebring, to the Chicago Cubs for Jake Weimer.

[5] Steinfeldt is the only member of the Cubs' infield, which also included Joe Tinker, Johnny Evers, and Frank Chance, who was left out of Franklin Pierce Adams' famous poem "Baseball's Sad Lexicon" (the famous trio played together for ten years, starting in 1902, while Steinfeldt played with them for five years).

In 21 World Series games, he hit .260 (19-for-73) with 7 runs, 3 doubles, 1 triple, 8 RBI, 2 stolen bases and 4 walks.