The Mariners and free-agent slugger Corey Hart have reportedly agreed to a one-year deal, according to CBS Sports baseball writer and MLB Network insider Jon Heyman on Twitter.
The 31-year-old Hart played nine seasons with the Milwaukee Brewers before sitting out all of 2013 while recovering from surgery on both knees.
He batted .270 with 83 RBI and 30 home runs in 149 games in 2012.
Adding Hart to the mix provides Seattle with another big bat and adds some versatility in the field as well, since he can play first base or in the outfield. He started 49 games in right field for Milwaukee in 2012 and made 123 starts there a year earlier.
Still, Hart's biggest asset is his ability to swing the bat. The Bowling Green, Ky., native has 154 homers since 2005 and 501 RBI since the start of 2006. At 6'6", 235 pounds, Hart boasts a powerful frame that's sure to bolster Seattle's new-look lineup.
The 26-year-old Morrison is less proven than Hart but full of potential. He started 78 games at first base for the Marlins in 2013 and drove in 36 runs in 293 at-bats. He played in 123 games in 2011, recording career-high marks in RBI (72) and home runs (23).
Signing Hart and trading for Morrison are the latest moves in what has already been a busy offseason for the Mariners. Last week, Seattle agreed to a massive deal with veteran slugger Robinson Cano. The Mariners signed the former New York Yankees star to a 10-year deal worth $240 million.
The Cano deal ties Albert Pujols' 2011 contract with the L.A. Angels as the third-largest in baseball history behind Alex Rodriguez's mammoth deals with the Texas Rangers and New York Yankees in the 2000s.
Like Cano, Hart and Morrison have only suited up for one franchise during their time in the majors.