The incident happened on the A7 approximately half a mile north of Galashiels, involving a red Seat Ibiza and a black Seat Ibiza at around 9.10pm on Monday, December 27.
Mason Mackenzie, the 20-year-old male driver of the red Seat Ibiza, was taken to the Royal Infirmary of Edinburgh for treatment.
Sadly he died in the hospital yesterday, Sunday, January, 2.
Mr Mackenzie, originally from Scunthorpe, lived in Galashiels and was a former pupil at Jedburgh Grammar School.
A report has been submitted to the Procurator Fiscal.
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 can call police on 101 quoting incident 3191 of 27 December, 2021.”