In 2015, Phythian played for the Newcastle Knights' NYC team,[6] before being promoted to their New South Wales Cup team during the year.[7]
In round 25 of the 2016 NRL season, Phythian made his NRL debut for the Knights against the South Sydney Rabbitohs, scoring a try.[8][9][10] In November, he re-signed with the Knights on a 1-year contract until the end of 2017.[11]
While playing fullback in round 1 of the 2017 season against the New Zealand Warriors, Phythian suffered a season-ending injury, tearing the anterior cruciate ligament in his left knee.[12] In September, he had his Knights contract extended until the end of 2018.[13]
On 27 March, Phythian had his contract terminated by the Knights after he returned a second positive test for social drugs, the first test remaining anonymous under the NRL's rules, with the second positive test automatically incurring a 12-match suspension.[14][15]
Phythian made his return to the field in June for Lakes United in the Newcastle Rugby League. Less than a week later, he made a mid-season move to the Burleigh Bears in the Queensland Cup.[16]
In February, Phythian was given the chance to train and trial with the Gold Coast Titans during the pre-season.[17]
In September, Phythian played five-eighth in the 2019 Intrust Super Cup Grand Final defeating Wynnum Manly. He also played in the State Championship Grand Final against the NSW Intrust Super Cup winners Newtown Jets.[18]
In 2020, Phythian played for the Blacktown Workers.[19]
In 2021, Phythian returned to Newcastle to play for the Central Newcastle Butcher Boys in the Newcastle Rugby League.[19]
In 2022, Phythian returned to the Knights on a train and trial contract and played for their NSW Cup team.[20]
