He played on the European circuit from 1969 to 1974, winning 10 tournaments and taking the Harry Vardon Trophy for heading the Order of Merit for four consecutive seasons from 1971 to 1974.

Oosterhuis won the 1966 Berkshire Trophy by a stroke from Michael Bonallack, after a final round 67 which included nine 3s in 11 holes, with seven 3s in succession.

[3] In 1968 he was a runner-up in the Golf Illustrated Gold Vase behind Michael Bonallack and tied with Ted Dexter.

He made his senior debut for England in the 1966 Home Internationals,[5] then represented Great Britain in the 1967 Walker Cup.

[8] Oosterhuis played in South Africa in early 1969, finishing runner-up to Bobby Cole in the Natal Open.

[9] Later in the year, he started the British season by winning the Sunningdale Foursomes, playing with the amateur Peter Benka.

[10] He finished runner-up in the Gor-Ray Under-24 Championship and, playing with Nigel Paul, won the Whitbread professional-amateur foursomes.

[17] In April 1971, Oosterhuis made his debut on the PGA Tour at the 1971 Greater Greensboro Open, the week before competing in his first Masters.

[22] In September he represented Great Britain and Ireland for the first time in the Ryder Cup in St. Louis, having finished second in the points list.

Oosterhuis won the Penfold-Bournemouth Tournament, after beating Christy O'Connor Jnr in a sudden-death playoff, and the Coca-Cola Young Professionals' Championship, a non-tour event.

[34][35] Later in the year, Oosterhuis won three European Tour events: the Piccadilly Medal, French Open and Viyella PGA Championship.

[24] Oosterhuis was selected to the two-man English team for the 1973 World Cup, to be played in November in Spain.

[33] The week after the Masters, he was runner-up in the Monsanto Open, where he lost at the fourth hole of a sudden-death playoff to Lee Elder.

[28] In addition he was runner-up in five other events, including the Open Championship, and was third in three more, finishing outside the top three only twice during the European Tour season.

[28] He won the Order of Merit for the fourth time, nearly 600 points ahead of second-place Dale Hayes.

[41] In November, Oosterhuis played in the 1974 PGA Tour Qualifying School in Palm Springs, California.

Oosterhuis easily qualified, finishing in fourth place, three strokes behind the winner Fuzzy Zoeller.

[52] He died from complications of the disease at a Charlotte memory care facility on 2 May 2024 at the age of 75;[53] a day before what would have been his 76th birthday.

[54] PGA Tour playoff record (0–1) Sources:[46][55] *Note: Tournament shortened to 54/63 holes due to weather.