Thornton advanced to the third round of the 2014 World Championship with comfortable victories over Max Hopp and Beau Anderson, but didn't produce his best darts against Wes Newton as he was beaten 4–1. His first final of the year came in February at the fifth UK Open Qualifier where he was defeated 6–2 by Gary Anderson. Thornton was a surprise 9–7 loser to Mensur Suljović in the UK Open fourth round. Thornton beat Phil Taylor 6–4 to play Ian White in the final of the sixth Players Championship. He fell 4–2 and 5–4 down and survived six match darts from White in the next leg to win his eighth PDC title 6–5. He won the next event too by defeating emerging player Keegan Brown 6–5, with his opponent this time missing four match darts. 24 hours later Thornton claimed the eighth event by averaging 106.56 in defeating Terry Jenkins 6–4. He only won two of his 16 Premier League matches to finish eighth in the table. Thornton played in his third World Cup of Darts this year and first with Peter Wright and they progressed to the quarter-finals where they played Northern Ireland's Brendan Dolan and Michael Mansell. Wright lost his singles match to Dolan, but Thornton saw off Mansell 4–3 to send the tie into a deciding doubles game which Scotland lost 4–1. He reached the final of the 11th Players Championship but lost 6–2 to Anderson.