There was never more than a set between Lewis and Raymond van Barneveld in the third round of the 2017 World Championship, with Lewis narrowly losing 4–3. He was beaten 6–4 by Peter Wright in the final of the first UK Open Qualifier of the year and won the fifth Players Championship with a 6–3 victory over Dave Chisnall. He threw a nine-darter in week 11 of the Premier League whilst defeating Van Barneveld 7–4 with an average of 111.52. Lewis played with Chisnall at the World Cup for the first time and they were knocked out in the semi-finals after failing to win either of their matches against the Dutch pair of Michael van Gerwen and Van Barneveld.