The disgruntled Ohka had asked to be traded after a recent incident involving Manager Frank Robinson.
The right-hander was fined by the team after turning his back on Robinson during a pitching change in the fourth inning last Saturday against Florida. General Manager Jim Bowden called it an act of contempt, after which Ohka asked to be traded.
Spivey was batting .236 with five home runs and 17 RBI in 49 games. He will replace second baseman Jose Vidro, who has been on the disabled list since May 5 with a high ankle sprain.
Ohka was 4-3 with a 3.33 ERA.
Jamey Carroll will now go back to back to being a back-up at second base. The Nationals also claimed right-handers Ryan Drese and Jacobo Sequea off waivers. Drese was the opening day starter for Texas.