The recently retired left-hander has accepted an invitation from the Mariners to throw the ceremonial first pitch prior to the regular-season home opener on April 12 against the Athletics.
The first-pitch plan was revealed on Thursday morning during the Mariners' 30th annual pre-Spring Training media session at Safeco Field. The announcement was preceded by a video showing some of the highlights of Johnson's 10-year career with Seattle.
Included in the clip were the final out of Johnson's first career no-hitter against the Tigers and the final out in the one-game playoff against the Angels in 1995, which clinched the Mariners' first American League West championship.
"As we all know, Randy led us to the division championships in 1995 and '97, and now that he has retired, we thought it would be fitting for him to do this," club president Chuck Armstrong said. "He won more games with us than any team he pitched for, and I think all of us with the Mariners thought it would be good to reconnect with Randy.
"We're honored and happy that Randy accepted our invitation."
Armstrong said marketing director Kevin Martinez suggested the tribute on the day Johnson announced his retirement from baseball.
"I just mentioned to Chuck that it would be fantastic if Randy was here on Opening Day, and he said, 'Absolutely,'" Martinez said.
"I liked the idea instantly," Armstrong said. "Who has been our most dominant pitcher when he was at the height of his game? That person is Randy Johnson. I went to [CEO Howard Lincoln], and he liked it instantly. So I called Alan Nero, Randy's agent."
The invitation was presented to Johnson, who quickly accepted.
Despite spending the last 11 years of his career away from Seattle, Mariners fans remained connected, giving Johnson resounding cheers when he returned as a visiting player, most recently last summer with the Giants.
"He has been very much a gentleman when he has come back," Armstrong said, "and he seems to connect with our fans. That's what we are trying to do."
The Big Unit, acquired from the Montreal Expos during the 1989 season, became the franchise's first pitcher to toss a no-hitter, win at least 20 games and capture the first of his five Cy Young Awards.
The future Hall of Famer compiled a 130-74 regular-season record with a 3.42 ERA while recording 2,162 strikeouts in 1,838 innings with the Mariners.
Overall, the Big Unit pitched for six organizations and finished his stellar career with a 303-166 record, 4,875 strikeouts, two no-hitters -- including a perfect game -- and one World Series Most Valuable Player Award.
"Randy is excited to come back, and it will be great for the fans," Martinez said.
Jim Street is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.