Clement will join the Major League club for Pittsburgh's Monday afternoon game against the Astros. Tejeda was designated to make room for Clement on the 40-man roster.
Clement -- the Mariners' first-round pick (third overall) of the 2005 First-Year Player Draft -- has appeared in five games with the Pirates this season, going hitless in six at-bats. He had 154 plate appearances in 2010, batting .201 with seven homers and 12 RBIs.
Clement has hit .276 with 16 homers and 57 RBIs this year in 112 games with Triple-A Indianapolis.
Tejeda, who was with Double-A Altoona, was batting .242 with three homers and 28 RBIs in 54 games.