A New South Wales State of Origin representative hooker, he played for the Canterbury-Bankstown Bulldogs, Brisbane Broncos, St George Illawarra Dragons, Newcastle Knights and the Cronulla-Sutherland Sharks, with whom he won the 2016 NRL premiership.

Ennis's first season at the Brisbane club, in 2006, was cut short by a knee injury suffered in round 5 against the South Sydney Rabbitohs at Suncorp Stadium.

While changing direction, Ennis snapped his anterior cruciate ligament and required a full knee reconstruction.

[6] As 2006 NRL Premiers, the Brisbane Broncos travelled to England to face 2006 Super League champions, St Helens R.F.C.

In the 2007 NRL season, Ennis made a return to first grade but was forced to work for his place in the side as a result of the good form of Shaun Berrigan at hooker.

After some appearances from the interchange bench earlier in the season, Ennis was trialled at halfback during the final stages of Brisbane's round 10 loss to the Manly-Warringah Sea Eagles.

With stiff competition from recruit PJ Marsh, Ennis cemented a spot as the starting hooker and guided the Broncos to some impressive early victories.

[9] Ennis made his State of Origin debut for New South Wales in Game III of the 2009 series, replacing bitter rival Robbie Farah who was dropped.

In the three-year period from the start of 2008 season, Ennis was penalised in games 58 times, the 2nd most of any player in the NRL behind Anthony Watmough.