A hernia and a lingering, physically draining cold caused Pearson to miss games in 1959 spring training, but he was healthy enough to play by Opening Day. However, Pearson started the 1959 season hitting only .188 over the first 25 games with no home runs and only two RBI, after which he was traded to the Baltimore Orioles for centerfielder Lenny Green. With the Orioles in 1959, Pearson was used as a reserve outfielder in all three outfield positions. In 80 games for the Orioles, he batted .232 with 22 runs scored, 32 hits, no home runs, and six RBI. His combined batting average in 105 games between Baltimore and Washington was .216.