The accident happened on the A7, just north of Galashiels, at around 9.10pm on Monday, December 27, 2021.
It involved two Seat Ibiza vehicles, one red and one black.
The driver of the red car was taken to the Royal Infirmary of Edinburgh for treatment where he sadly died on Sunday, January 2.
Sergeant Mark Banner, of Scottish Borders Road Policing, said: “Our thoughts are very much with the deceased’s family at this sad time.
“We are continuing to investigate the circumstances surrounding the crash and would ask anyone who has not yet come forward with information to get in touch with police.
“We're also keen to hear from anyone who may have witnessed the incident or motorists with dash-cam footage from around the time of the crash.”
Anyone with information should contact police on 101 quoting incident number 3191 of December 27.