He played his junior rugby league for the Western City Tigers prior to being signed by the Penrith Panthers.

In September 2016, Jennings signed a one-year contract with the Parramatta Eels starting in 2017, after not receiving any game time in the 2016 NRL season.

[13] On 28 August 2018, Jennings won the Jack Gibson NRL Coaches Award after being voted the club's best back.

[15] Jennings began the 2019 NRL season in reserve grade as coach Brad Arthur chose both Blake Ferguson and Maika Sivo as the club's first choice wingers.

In Round 10, Jennings was called into the Parramatta side to cover for the suspended Sivo as the club travelled to Townsville to face North Queensland.

Jennings instead played for the club's feeder side the Wentworthville Magpies in the Canterbury Cup NSW competition.

On 20 July, it was announced that Jennings would miss 4-6 matches after suffering a knee injury in the club's victory over Newcastle.

[22] On 24 August, Jennings was ruled out for an indefinite period after suffering a knee injury in the club's round 23 victory over the Gold Coast.

[23] Jennings played a total of 18 games for Melbourne in the 2021 NRL season as the club won 19 matches in a row and claimed the Minor Premiership.

[26] Jennings did manage to return for feeder club the Brisbane Tigers and played on the wing in their 2023 Queensland Cup grand final victory.