At the 2016 UK Open Kellett defeated Nathan Aspinall 6–5, Joey ten Berge 9–7 and Michael Smith 9–5 to reach the fifth round of the event for the first time, but lost 9–5 to amateur Barry Lynn. He failed to carry this last 16 showing into the rest of the year though, as he was knocked out in the first round of two European Tour events and reached the last 32 of three Players Championship tournaments, but lost each time. Kellett was ranked world number 72 after the 2017 World Championship and therefore entered Q School in an attempt to win his tour place back. He was within two matches of doing so on the fourth day, but lost 5–4 to Kirk Shepherd.