Greenock-born Lieutenant Henry "Birdie" Bowers was a member of the Terra Nova Expedition that reached the South Pole in 1912.
On the return trip to base camp Bowers and Scott, along with the other three members of the crew, died from starvation and the effects of extreme cold.
Sir Ranulph attended one of a series of memorial events to commemorate the intrepid Scot at Inverkip Marina in Inverclyde.
He said: "Birdie was a tough bloke and a very important part of the expedition."
During the expedition, Bowers, who at just 29 was the youngest member of Captain Scott's team, was selected as one of the five to make the ill-fated journey to the pole.
As well as being an important member of the team, he became a close friend of Scott.
Sir Ranulph, who is recognised as the world's greatest living explorer in the Guinness Book of World Records, was the first person to reach both the North and South Poles by surface means and the first to cross Antarctica on foot.
He said of Bowers: "He didn't have a bad word to say about anyone, which is very important on an expedition like that in such extreme conditions. The 100th anniversary is a wonderful opportunity for me to come to Inverkip to celebrate Birdie."
The ceremony was also attended by Captain Scott's grandson Falcon Scott and by Lieutenant Bowers's closest living relative, John Ramwell from Bolton, Lancashire.
Their forefathers reached the South Pole on January 17, 1912 only to discover the tent of Norwegian explorer Roald Amundsen, who had reached it five weeks earlier.
Sir Ranulph is currently planning his own Antarctic expedition, called The Coldest Journey.