[10] His second appearance at a ranking event was at the China Open by seeing off Robbie Williams and Joe Perry in qualifying and this time came through the wildcard round with a 5–1 defeat of Wang Yuchen, compiling his highest competitive break of 142 in the process[11][9] He faced Neil Robertson in the last 32 and was whitewashed 0–5.

[12] Robertson had a consistent season in the ten Players Tour Championship events, with his best result being a last 16 loss to Andrew Higginson in the Scottish Open, to finish 45th on the PTC Order of Merit.

[18] Robertson finished 20th on the Order of Merit which saw him qualify for the Finals for the first time in his career, but he lost 4–2 to John Higgins in the opening round.

[27] At the Haining Open, Robertson reached the semi-finals by knocking out Xiao Guodong and Thepchaiya Un-Nooh from the fourth round stage, but he lost 4–2 to Ding Junhui.

He reached the last 16 of a ranking event for the first time in his career by beating Darryl Hill 6–2 and Barry Hawkins 6–4 at the International Championship and then lost 6–3 to Marco Fu.

[30] Robertson reached the last 16 of a ranking event for the second time by beating Dechawat Poomjaeng 4–0 and Martin O'Donnell 4–3 at the Riga Masters and was defeated 4–1 by John Astley.

He won through to the third round of both the UK Championship and Welsh Open, but failed to pick up a frame in losses to Oliver Lines and Scott Donaldson respectively.

[31] Robertson defeated Cao Yupeng 10–8, Oliver Lines 10–4 and Rod Lawler 10–6 to qualify for the World Championship and played Mark Allen in the opening round.

He also spoke about how he had been frustrated with his performances in big matches and had been working with a sports psychologist during the World Championship to help him prepare for the season ahead.

After qualifying victories over Rhys Clark and Peter Lines, he defeated defending champion Anthony Hamilton 5–1 in the last 32[36] and Gary Wilson 5-3 in the last 16 before losing out to Williams 5–3.

After losing in the opening round of the next five ranking events,[35] he once again came through qualifying for the World Championship, defeating Alex Borg 10–2, Sam Baird 10–7 and Michael White 10–7.

Robertson had an up and down start to the 2018–19 snooker season, failing to qualify for the Riga Masters, World Open and China Championship, but reached the last 16 at the Paul Hunter Classic where he lost 4–0 to Jack Lisowski.

After defeating Andy Lee 4–3 in qualifying, at the main stages of the tournament in Lommel, Belgium, his first three matches were also won in a deciding frame (4–3 victories against Zhang Yong, Zhou Yuelong and Anthony McGill respectively).

[43] The boost to his seasons's ranking points also helped him to qualify for the Players Championship for the first time in its current format; he was whitewashed 6–0 by reigning world champion Judd Trump in the first round.

Despite losing by the same scoreline to Lu Ning in the next round, the win was enough to narrowly maintain his place on the tour, finishing the season ranked 63rd.

[50][47] Robertson later revealed that working with a mind coach on his mental approach had helped him to get over the line in his decisive match and that he had "belief" in his ability going forward.

[54] Robertson has two children with his partner Hayley[38] and owns O'Sullivan's Snooker & Pool Club in his hometown of Bexhill-on-Sea, East Sussex.