South African fast bowler Marchant de Lange is leaving Glamorgan to join Somerset as an overseas player for 2021.
De Lange, 30, has spent four seasons with Glamorgan as a UK player thanks to his wife being British.
But he no longer counts as a 'home' player after Brexit, and his contract was cancelled by mutual consent.
Somerset have recruited de Lange after the departure of paceman Jamie Overton to Surrey.
Somerset Director of Cricket Andy Hurry said: "Marchant will no doubt add real value, a different dimension to an already potent bowling attack and it demonstrates our intent to continue to strive to winning silverware."
"Marchant's skill, experience and ability to bowl at express pace will complement our bowling group perfectly. I believe he will be a great fit for our environment."
De Lange made 12 appearances for South Africa across the three formats before joining the county circuit.
He claimed 85 wickets at an average of 33.7 in first-class cricket for Glamorgan, plus 39 One-Day Cup wickets at 26.8 and 36 T20 victims at 23.7.
Although he was the fastest bowler in the Welsh county's squad, it was his muscular batting that earned him a place in their record books as he scored their quickest-ever first-class century off just 62 balls against Northants at Northampton in 2020.
"It is a huge privilege for me to be joining Somerset and I can't wait to start my journey with such an ambitious and proud club," de Lange told the Somerset website.
"I am very excited of the prospect of being part of a formidable team and striving towards winning multiple competitions and silverware.
"I'm incredibly sad to be leaving Glamorgan and Sophia Gardens," he added.
"I have such fond memories of my time here, and I have thoroughly enjoyed representing the people of Glamorgan and Wales."
De Lange was also due to represent Manchester Originals in the inaugural Hundred franchise tournament, which has been postponed until 2021.
Glamorgan director of cricket Mark Wallace said: "The change in regulations has altered the category that he is able to play under, and it is unfortunate that Marchant is a victim of these changes.
"He has always given the club 100% of his efforts and he's been an incredibly popular member of the side and a favourite of the staff around Sophia Gardens, so we wish him all the best."
Two overseas players will be allowed in all competitions next season because of the end of the Kolpak system, which allowed qualification through an EU passport.
Glamorgan, who have Australian batsman Marnus Labuschagne and South Africa's Colin Ingram on their books as overseas players, are expected to confirm their plans shortly for the 2021 season.