SEATTLE -- The Mariners activated former American League Rookie of the Year Kyle Lewis from the injured list Tuesday, nearly a year after he last played in a major league game.

Lewis, the 2020 rookie of the year, missed most of last season because of a right knee injury, but the slumping Mariners are hoping his return to the lineup can provide a spark.

Lewis was batting seventh for Tuesday's game against Oakland. His last major league game was on May 31, 2021.

"It's exciting to have him back. It's been a long time," manager Scott Servais said. "He's worked his tail off to be back here, it hasn't been easy. Lot of bumps in the road along the way, but I know he's excited."

Lewis will primarily be a designated hitter for Seattle as continued knee troubles have limited his ability to play in the field.

Lewis suffered a torn meniscus in his right knee last spring and underwent surgery. His recovery was slowed by setbacks, and he was eventually shut down by Seattle late in the season. Lewis also suffered a bone bruise in the knee during this spring training that cost him the first few weeks of the season.

The first major issue Lewis had with the knee was in 2016, when he tore the ACL.

"He's not going to be playing any outfield anytime soon. He's going to primarily be our DH. But we'll see where it leads," Servais said.

If Lewis can rediscover the success at the plate he had in 2020, it would be a big boost for Seattle's lagging offense. During the pandemic-shortened 2020 season, Lewis hit .262 with 11 home runs and 28 RBIs in 58 games. He was batting .246 with five homers in 36 games when his 2021 season ended.

Seattle has gotten poor production from the designated hitter spot. Entering Tuesday, the DH position for Seattle was hitting a meager .155.