Jack Sealy is the son of former Queen's Park Rangers and Eastern player Tony Sealy. Jack is of Barbudian descent through his paternal grandfather. He was born in England and but later became a naturalized Hong Konger. From an early age he represented the Hong Kong Football Club and by the age of 12 was playing football in adult social leagues, the Yau Yee League, before making the step up to the Hong Kong Second Division at the age of 16.
Jack Sealy played for HKFC from 2007, with his father Tony Sealy as his coach. He scored an own goal in the 0–6 loss to Kitchee on 23 September 2010. He missed a scoring chance and then scored an own goal in the 2–4 defeat to Fourway Rangers on 17 December 2010.
Jack Sealy moved to South China in July 2012 to further his career. On 29 September 2012, Dhiego Martins scored in stoppage time from an inch-perfect cross from Sealy, helping the club beat rivals Kitchee 1–0. Sealy scored his first league goal for South China against Yokohama FC Hong Kong on 15 February 2014.
On 27 December 2015, South China announced that Jack Sealy has signed with Chinese Super League club Changchun Yatai for five-years, he will report to his new club in January 2016.
On 22 July 2018, it was reported that Sealy had left Tai Po for fellow Hong Kong Premier League club Pegasus.
Southern
On 2 July 2019, Sealy moved back to the island, signing a contract with Southern.
International career
On 6 December 2011, Jack Sealy trained with the Hong Kong national football teamfor the first time, to prepare for the 2012 Guangdong-Hong Kong Cup. He claims that he and his father both have special feelings for Hong Kong football and his father is very supportive of his joining the Hong Kong national team. He is willing to apply for a Hong Kong passport to play for Hong Kong. He made his debut with Hong Kong on 28 December 2011 against Guangdong. In the match, he made a long pass from which Cheng Siu Wai scored the equalising goal. The match ended 2–2. He obtained Hong Kong passport in March 2013. He is eligible to represent Hong Kong in international "A" matches. He made his debut for Hong Kong on 6 September 2013 against Myanmar, however, the match was not recognized as an international 'A' match by FIFA, as Myanmar made more than 6 substitutions. His first international match for Hong Kong should be on 10 September 2013 against Singapore
