In his début season, he reached the last 64 of the Royal London Watches Grand Prix, beating Lewis Roberts 5–2 and Barry Pinches 5–4 before losing 2–5 to Jimmy Michie; in the China Open, Lee beat Matthew Selt and Paul Davies before losing at the same stage to Gerard Greene.

Having earned £5,000 in prize money, Lee finished the season ranked 83rd and was relegated from the main tour.

He entered the 2018 Q School in an attempt to win back a place on the main tour; in the first event he lost in the last 32, 0–4 to Thor Chuan Leong.

In the third event he beat Kuldesh Johal 4–2 in the quarter-finals to regain his professional status after a hiatus of nine years.

Lee reached his first ever the last 32 of a ranking event in the Gibraltar Open, beating Curtis Daher 4–0 and Kuldesh Johal 4–3 before losing 0–4 to Andrew Higginson.