His career began in 1937 in the lower minor leagues and was interrupted by service in the United States Army Air Forces during World War II;[2] he missed the seasons of 1942 through 1945.

Returning to baseball in 1946, he won 16 games the following season for Double-A Chattanooga and was rewarded, at age 29, with a callup to the parent Senators in September 1947.

After a scoreless relief appearance on September 17 against the Cleveland Indians, Toenes was given the starting pitcher assignment three days later at Fenway Park against the Boston Red Sox.

He went four innings, allowing nine hits (including doubles to Johnny Pesky and Dom DiMaggio, and a triple to Ted Williams), and was tagged with the eventual 7–2 Washington defeat.

[3] But he returned to face the Red Sox in relief seven days later at Griffith Stadium and hurled 12⁄3 innings of shutout ball in what would be his last MLB appearance.