In 2008–09 Hamilton did not reach the last sixteen in any of the first five ranking events. He lost in the first round 3–5 against Andrew Higginson at the Northern Ireland Trophy, 2–5 against Marco Fu at the Shanghai Masters, and 0–5 against John Higgins at the Grand Prix, while he could not qualify for the Bahrain Championship and the UK Championship, as he lost in the qualifying round 2–5 against Mark Davis and 4–9 against Higginson respectively. However he managed a run to the semi-finals of the 2009 Welsh Open. On the way he beat Peter Ebdon, Michael Judge and Mark Selby. In the semi-final he led Ali Carter 3–0 and it looked as though he may reach his third ranking final but eventually lost 5–6 against the eventual winner. Hamilton qualified for the China Open, by defeating Patrick Wallace 5–1, but lost 4–5 against John Higgins, and he couldn't qualify for the World Championship, as he lost 5–10 to Ricky Walden in the last qualifying round. At the end of the season he lost his place among the world's top 32, and was ranked number 33 in the next season.