Andrew Barton, from Oxfam, said: "All of Oxfam have been cheering Federer's progress for the past couple of weeks.
"The real hero, though, must be Mr Newlife, for his generous gift and his tremendous sporting acumen. It may inspire other people to support Oxfam and our West Africa appeal."
The bookmakers has already paid out £16,750 to the charity from another bet placed by Mr Newlife which wagered £250 at 66/1 that Federer would win 14 Grand Slam events. Oxfam said the payout is enough money to enable the charity to bring food to 10,000 people for an entire month.
Mr Newlife died in 2009, aged 59, leaving his estate to Oxfam, who now collect £101,840.
William Hill said: "Mr Newlife told had identified Roger Federer as a future serial winner & wanted to place a 'sizeable' long term wager on him.This is one of the most remarkable bets we have ever accepted."