Bernie Ecclestone said Max Mosley was like a brother to him following the former FIA president's death.
Mosley died on Sunday night after a battle with cancer. He was 81.
Mosley is considered to be among the greatest figures in Formula One history.
He headed up its governing body, the FIA, for almost two decades, and helped to transform the sport's safety record after Ayrton Senna's death at the San Marino Grand Prix in 1994.
Jules Bianchi is the only F1 driver to die as a result of injuries sustained at a grand prix in the years since Senna died.
"Max was like family to me," Ecclestone, F1's ringmaster for 40 years, told the PA news agency.
"We were like brothers. I am pleased in a way because he suffered for too long. We spoke all the time and he was trying different cures to get better.
"It was not nice to see because he had worked so hard to help people, but nobody could help him when he needed it the most."
Mosley spent his latter years campaigning for tougher press regulation after his own successful legal battle against the News of the World in 2008 when it was wrongly claimed his involvement in a sadomasochistic sex session was related to Nazism.
Mosley, the son of the 1930s British fascist leader, Sir Oswald Mosley, fought to remain in charge of the FIA despite huge pressure on him to leave his post.
He ultimately won an FIA vote to continue his presidency before he was succeeded by Jean Todt a year later.
Ecclestone did not back his close ally in the intermediate aftermath of the News of the World story, and says his failure to do so upsets him.
"In all the things I have done in my life, I cannot say I have been ashamed or sorry about anything, but in the case of Max and the fact I never supported him, I am upset about that and I will never forget it," added Ecclestone.
"In the end, I openly apologised to Max in front of everyone at the FIA and he understood what was happening and the reason I was put in a difficult position, but it doesn't make a difference because there are no excuses.
"We did a lot of things and achieved a lot of things together so it is hard to pick out just one special moment because they were all a bit special.
"Max didn't waste time on doing things and if he thought people were wasting his time he would get upset with that. He didn't suffer fools gladly."
Three-time F1 champion Sir Jackie Stewart said Mosley and Ecclestone were a formidable pairing.
"Max was a remarkable man in many ways and a really well-educated man," the 81-year-old said. "He was always very close to Bernie, they were like conjoined twins.
"He was controversial, there is no doubt about that, but he did things in motor sport that we should all be grateful for."
Mosley's love of motor racing began in his youth and he competed in Formula Two for Brabham and Lotus before retiring in 1969.
He founded the car manufacturing company, March Engineering, and oversaw its legal and commercial affairs from 1969 to 1977.
He then became the official legal advisor to the Formula One Constructors' Association (FOCA) in the mid-70s, and helped draw up a peace agreement between it and FISA, F1's governing body at the time.
He became FISA president in 1991 and two years later took over unopposed at the FIA before he was replaced by Todt in 2009.
Todt, who is serving his final term as FIA president, said: "I am deeply saddened by the passing of Max Mosley. He was a major figure in F1 and motor sport.
"As FIA President for 16 years, he strongly contributed to reinforcing safety on track and on the roads. The entire FIA community pays tribute to him. Our thoughts and prayers are with his family."
An F1 spokesperson added: "We are saddened to hear that Max Mosley, former FIA President has passed away. A huge figure in the transition of Formula One.
"Our thoughts are with his family and friends at this sad time."
Mosley's life is to be the subject of a new documentary which will be released in July, titled 'Mosley: It's Complicated'.
