New Zealand batsman Rutherford will be available for the entire 50-over campaign and the final four Championship matches of 2021
Hamish Rutherford will join Glamorgan for the Royal London Cup and four LV= Insurance County Championship fixtures.
The New Zealand batsman replaces Marnus Labuschagne, whose stint with the Welsh county will come to an end after the T20 Blast, when he returns home to Australia to prepare for the new season Down Under.
Rutherford has previous experience of county cricket with Worcestershire and Essex.
He will be available for the entire 50-over campaign and the final four Championship matches of 2021.
Glamorgan director of cricket, Mark Wallace, said: "Marnus leaving is obviously a loss but to replace him with someone the calibre of Hamish is a massive bonus for the club.
"He has a proven track record of scoring runs in both first-class and List A cricket over here and is the right character to have in the dressing room for our younger players to learn from."
Rutherford said: "I’m really looking forward to joining up with Glamorgan for the remainder of the season.
"I’ve been fortunate to play lots of county cricket and always enjoy the challenge - hopefully I can use my experience to help some of the younger players in the squad.
"To be able to come over and get stuck into a comp where all teams are starting afresh is also exciting. Hopefully we can get going in the 50-over comp and carry some momentum into the final phase of first-class cricket."
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