Hamilton turned professional in 1991, entering the world's top 32 in &lt;a href="Snooker%20world%20rankings%201995/1996"&gt;1995/1996&lt;/a&gt;. Hamilton has reached two ranking tournament finals. In the British Open in 1999, where he lost to Fergal O'Brien, Hamilton opened with two centuries, but O'Brien won five frames on the final black to defeat the Nottingham man. The other was the 2001 China Open. Mark Williams beat him 9–8, despite Hamilton having led 8–5. He made the first of his four World Championship quarter-finals in 2000, losing 3–13 to John Higgins.