Crews were called to the scene on the A7 between Galashiels and Selkirk before 10:00.
Police were sent to the incident to help with traffic management in the area.
Diversions were in place and drivers advised to avoid the route for about four hours while efforts continued to bring the flames under control.
A Scottish Fire and Rescue Service spokeswoman said firefighters had been tackling what they described as "a large gorse fire".
"Four appliances were mobilised after the call was received at 09:54 on Thursday, 11 May," she said.
Crews used "powerful water jets and beaters" to tackle the flames.
One of the main routes through the Scottish Borders has reopened after being shut due to a gorse fire.