Rocastle was with Isthmian League Premier Division club Gravesend and Northfleet when in September 2001 he went on trial to Queens Park Rangers,[3] who during his stay with them went into administration. After a loan spell in November 2001 with Southern League Eastern Division club Ashford Town (Kent),[4] it was announced in early December 2001 that he had left Gravesend and Northfleet.[5] Later that month (initially on a one month trial)[6] Rocastle signed with Isthmian League Premier Division side Kingstonian[7] for whom he made 23 goal-less league appearances.[8] In February 2003 he signed with Slough Town, making 13 Isthmian League Division One North appearances without scoring.[9] He then signed with Premier League club Chelsea in 2003, although he did not make a first-team appearance, appearing once as a non-playing substitute.
He spent the first half of the 2004–05 season at Tony Mowbray's Hibernian,[13] playing thirteen league games in a very successful season for the SPL club.[14] The club had kept faith with the midfielder as he damaged a thigh muscle in September[15] and was feared to have damaged knee ligaments in December,[16] and were hopeful of acquiring him permanently. With no future with Chelsea,[17] he instead joined Sheffield Wednesday on a free transfer in February 2005, signing a 2+1⁄2-year deal.[18] His first senior goal came in a 3–2 win over Blackpool at Hillsborough on 12 March.[19] He played for the "Owls" in the League Oneplay-off final, which finished as a 4–2 victory over Hartlepool United at the Millennium Stadium in front of close to 60,000 spectators.
Rocastle played seventeen games of the club's 2005–06Championship season before going out on loan to League One side Yeovil Town in late-March. At the end of the season Rocastle's contract at Wednesday was terminated by mutual consent. He quickly signed for Oldham Athletic.[20] He played 35 league games in 2006–07, helping Oldham to a play-off place. However, most of these appearances were as a substitute. In the play-offs they were defeated by eventual promotion winners Blackpool in the semi-finals.
In June 2007, he signed a two-year deal to join Port Vale.[21] He was not a first-team favourite in 2007–08, but did manage 21 starts and a goal against Cheltenham Town at Vale Park.[22] He spent two weeks in January on loan with League One rivals Gillingham,[23] playing two games for the "Gills". After talks with managerLee Sinnott, his contract was terminated by mutual consent in April 2008.[24]
Rocastle had a trial with Hibernian in May 2008, having impressed on loan there previously,[25] but manager Mixu Paatelainen did not offer him a contract.[26] Rocastle instead joined Thrasyvoulos Filis in the Superleague Greece.[27] He made thirteen appearances for the club in 2008–09. However, they finished bottom with a mere 14 points from 30 games and were relegated to the Football League.