The 2012–13 season saw Harold win 2 qualifying matches to reach the main stages of the 2012 Wuxi Classic, however, he lost his wildcard match to Chinese player Rouzi Maimaiti. Harold subsequently failed to qualify for the next four ranking events, losing to players such as Ali Carter, Barry Hawkins, and Cao Yupeng. He did, however, qualify for the German Masters, beating Craig Steadman 5–3 and Ryan Day 5–4 to qualify for the Last 32 of the event, where he lost 3–5 to former world champion Graeme Dott. He only won 1 more match in ranking event qualifiers for the rest of the season, culminating with a 9–10 defeat the Alfie Burden in qualifying for the World Championship. Harold played in many of the Players Tour Championship event throughout the season, his best results being three Last 16 appearances, and a further two Last 32 results, finishing 39th on the Order of Merit, outside of the Top 26 that qualified for the Finals.