Cahill's 2016–17 season was a breakout year, where he appeared in many more main stage tournaments than any of his previous seasons. He appeared for the first time at both the 2016 Riga Masters, losing 3–4 to Zhao Xintong; and then 2016 World Open losing to Liang Wenbo 2–5. Cahill progressed to the third round of the 2016 Paul Hunter Classic by eliminating Kevin Vandevoort 4–0 and Ryan Day 4–2. In the third round, He drew world number one Mark Selby. Despite being 1–3 behind, he made two breaks above 50 to come back to tie the match at 3–3, but lost the deciding frame. The next event of the season saw him beaten 1–4 by Joe Swail in the second round of the English Open, after beating Adam Stefanow 4–3 in the opening round.