The Mariners reassigned Buchter to minor-league camp Tuesday.
Buchter signed a minor-league contract with the Mariners on Sunday that includes an invite to big-league camp.
Buchter was released by the Diamondbacks on Friday.
Buchter was returned to Triple-A Reno on Friday, Steve Gilbert of MLB.com reports.
The Diamondbacks designated Buchter for assignment Monday.
Buchter (0-2) lost Saturday's 6-5 game at the hands of San Francisco, allowing two runs on two hits and three walks with two strikeouts.
Buchter's contract was selected by the Diamondbacks on Thursday.
The Diamondbacks reassigned Buchter to their minor-league camp Wednesday.
Buchter signed with Arizona as a non-roster invitee Tuesday, Bob Nightengale of USA Today reports.
Buchter signed a minor-league deal with the Yankees earlier this week and was added to the 60-man player pool.