Robertson is known as the hero behind Forest's glory days when they won the European Cup twice in the late 1970s.
Nottingham Forest confirmed the news in an official statement on Thursday local time. The club described Robertson's departure as a huge loss for the Forest family.
"We are saddened to announce the passing of Nottingham Forest legend and friend, John Robertson," the club wrote on Friday. The cause of death was not disclosed.
Robertson is an iconic figure in Forest's history. He played a crucial role as the East Midlands club won back-to-back European Cups in 1979 and 1980 under Brian Clough, a remarkable feat that would later become a key part of Champions League history.
In the 1979 European Cup final in Munich, Robertson was the star of the show, delivering a cross that Trevor Francis converted to score the only goal as Forest defeated Swedish club Malmö. The victory clinched Forest's first European Cup title.
