At the 2013 World Championship Thornton missed four darts to win 4–2 in the second round against Paul Nicholson and another one in the deciding set. Nicholson threw for the match and left 58 after 12 darts, only for Thornton to take out 130. Thornton won the bull to throw first in the sudden-death leg and won it to set up a last 16 meeting with Phil Taylor. However, Thornton could only win three legs as he bowed out of the tournament with a 4–0 defeat. Thornton partnered Gary Anderson for the third time at the World Cup of Darts and they were shocked by Spain 5–4 in the last 16.