Worsley made his debut on 7 December 2011, in the final heat game of Series 65 and of Jeff Stelling's tenure as host, beating Phyllis Styles 103 – 39 before stepping aside for the finals. He returned in January for the Nick Hewer era and won the first episode of Series 66, along with six more, never facing a crucial conundrum and scoring centuries in all but one of his heats. Worsley is one of a handful of series champions (John Rawnsley, Junaid Mubeen and Kirk Bevins being others) to have debuted in another, previous series.
With an octochamp total of 818 points, Worsley was #2 seed for the series finals behind Jonathan Rawlinson, but the difference in their totals was substantial. After defeating Mark Murphy and Peter Lee, he faced a grand final encounter against Rawlinson. He took first blood with SANTERO, but the #1 seed fought back with PITHOI soon after, and both players were in contention to the end. Worsley led 80 – 70 going into the final round of play. However, the crucial conundrum STORYLINE defeated both players, meaning that Worsley became the series champion.
He returned to Countdown in 2013, as one of 41 contestants taking part in the 30th Birthday Championship. After receiving a bye to the first round, he won his first match against the Series 65 champion Graeme Cole by a score of 104 – 98, despite Cole maxing the first 13 rounds. He then beat the Series 4 runner-up Christine Hunt in round 2, leaving the competition with just male contestants. In the quarter-final, he came up against the Series 53 semi-finalist Jon O'Neill and after missing DRUPELET in round 1, he managed to keep up with O'Neill, before O'Neill got the conundrum ECOSPHERE to win by 122 – 104, achieving a max game in the process, and ending Worsley's unbeaten record on the show.
He attended his first CO-event in 2012, when he played at CO:REA, along with his dad, Paul. A week later, he and his dad attended CoLei5. Another two months later, he entered COHUD, followed by CoChest2 in October and COEDI in November. He played at CO:REA 2013, CO:REA 2014 (where he beat the Series 68 winner, Giles Hutchings, by 108 – 93 in the final) and CO:REA 2015 (where he beat Series 54 winner, Conor Travers, by 117 – 97 in the final).
He is also an Apterite, and has held the #1 Pro Rank position.
|#||Date||Type||Contestant 1||Score||Contestant 2||Guest||Lex||Max|
|5391||7/12/2011||P||Phyllis Styles||39 – 103||Jack Worsley||David Lloyd||Susie Dent||122|
|5399||9/01/2012||P||Jack Worsley||105 – 54||Brian Tuohy||Paul Zenon||Susie Dent||127|
|5400||10/01/2012||P||Jack Worsley||110 – 44||Catherine Green||Paul Zenon||Susie Dent||150|
|5401||11/01/2012||P||Jack Worsley||103 – 67||Barry Williams||Paul Zenon||Susie Dent||140|
|5402||12/01/2012||P||Jack Worsley||100 – 51||Marcia Wells||Paul Zenon||Susie Dent||122|
|5403||13/01/2012||P||Jack Worsley||107 – 50||Abi Maher||Paul Zenon||Susie Dent||129|
|5404||16/01/2012||P||Jack Worsley||105 – 73||Stewart Macpherson||John Suchet||Susie Dent||120|
|5405||17/01/2012||P||Jack Worsley||85 – 51||Alan Paterson||John Suchet||Susie Dent||120|
|5512||22/06/2012||QF||Mark Murphy||52 – 75||Jack Worsley||Penny Smith||Susie Dent||113|
|5516||28/06/2012||SF||Peter Lee||88 – 91||Jack Worsley||Dr Phil Hammond||Susie Dent||119|
|5517||29/06/2012||GF||Jack Worsley||80 – 70||Jonathan Rawlinson||Dr Phil Hammond||Susie Dent||117|
|5633||31/01/2013||30B1||Graeme Cole||98 – 104||Jack Worsley||Mark Foster||Susie Dent||118|
|5646||19/02/2013||30B2||Christine Hunt||67 – 115||Jack Worsley||Dr Phil Hammond||Susie Dent||117|
|5649||22/02/2013||30BQF||Jon O'Neill||122 – 104||Jack Worsley||Dr Phil Hammond||Susie Dent||122|