Robson qualified twice for the World Championships, but was beaten in the first round on each occasion. He made it for a third time in
2004, but found himself 2–0 down in sets against
Steve Coote. However, Robson recovered and took the match to a sudden death deciding leg, which he won.
Bobby George commented that "you won't see browner darts in this tournament than that match". Robson had another excellent performance in losing to 'Silverback'
Tony O'Shea in the second round. Robson's biggest tournament win so far was at the
World Darts Trophy in
Utrecht,
Netherlands. He beat
Mervyn King 6–4 in the 2005 final, averaging 91.5 for three darts, which was a fair way below his averages during his aforementioned performances in the 2004 World Championship. Robson had to wait until
2007 to win another match at the World Championship, but his opponent for that match was pre-tournament favourite
Michael van Gerwen. Robson won 3–2, although the teenage van Gerwen was not quite at his best form and looked nervous on some doubles. Robson did not have to wait long for his next win, as he made the quarter-finals for the first time in his career with a superb 4–3 win over former champion
John Walton, having been 3–1 down. Robson could have had a nine-dart leg, but missed his seventh treble. However, his run was ended by Dutchman
Niels de Ruiter. Robson led 2–0 and 4–2 but ended up losing 5–4. This match included a leg which
Tony Green and
John Part touted as "probably the best in thirty years", which Robson won to take the fifth set and lead 3–2. Robson returned to the World Championship in
2008 where he was drawn against 2002 World Champion,
Tony David. This was Robson's only win at the 2008 World Championship, as in the second round he came up against an in-form
Darryl Fitton. Fitton averaged over 100 in a 4–0 victory. In the
2009 World Championship, Robson reached the quarter-final for the second time, beating
Stephen Bunting and
Martin Atkins before losing to
Martin Adams. 2009 was not a good year for Robson as a whole and as a result, he was forced to qualify for the
2010 Lakeside World Championship. Robson lost 3–0 in a first round clash with 2009 champion and 5th seed
Ted Hankey at the 2010 BDO World Championship. The next year, Robson was seeded once more and cruised through to the quarter-finals for a third time by defeating Steve Douglas and
Dave Chisnall for the loss of just one set. He then led
Martin Phillips 3–1 but was once again defeated 5–4. Robson was knocked out of the 2012 World Championships in the first round losing 3–0 to Steve Douglas Gary was again knocked out in the first round in 2013 this time losing 3–1 to
Garry Thompson PDC He competed for a tour card at the 2020 Q school in an attempt to join the
Professional Darts Corporation, however he finished 164th and failed to win a tour card. ==World Championship results==