Brussow has 23 caps for the Springboks and will replace France number eight Louis Picamoles.
Former South Africa back row Heinrich Brussow will join Northampton in January upon completion of his contract with Japanese club Docomo Red Hurricanes.
The 31-year-old won the last of his 23 caps in 2015 and spent 12 years with the Super Rugby team the Cheetahs before heading to Osaka to sign a full-time contract in the Top League, where he has spent the past two seasons.
“My wife and I feel it is time for a new challenge. I want to play my best possible rugby and hopefully contribute to winning a few trophies,” the openside said.
Brussow has been signed as a replacement for Louis Picamoles, the France number eight who joined Montpellier in the summer after completing only one year of his three-year deal.