In-form Dolphins outside back battled through a knee injury to complete the game against the Brisbane Broncos last Friday night, but he will now need to spend a number of weeks on the sideline.
The Dolphins confirmed this week that Niu will join Sean O'Sullivan on the sideline, although for not nearly as long.
While O'Sullivan will face a gruelling rehab for a full tendon rupture of his pectoral muscle and will miss three to four months, Niu will likely be back in about four weeks' time.
The centre and fullback, who has instead impressed on the wing this season for the Dolphins under the coaching of Wayne Bennett, has suffered damage to the medial collateral ligament in his knee.
The club confirmed he will miss at least four games, which will take the shape of trips to play the St George Illawarra Dragons and North Queensland Cowboys, before the club host the South Sydney Rabbitohs and Gold Coast Titans in Rounds 7 and 8.
The Dolphins then play the Canberra Raiders on the road in Round 9 which could mark Niu's return game.
The NRL's newest club, who have impressed so far this year, will likely call on either Robert Jennings, who was the 18th man last week, or Edrick Lee, who returned with the Central Queensland Capras in the QLD Cup last week, as his replacement.
Lee played the full 80 minutes in a 24-4 win over the Northern Pride but struggled to have influence, only making 59 metres from 8 runs.
The former Knight brings height and strength to the wing, but Wayne Bennett may elect to keep him on ice and out of the NRL for the time being as he builds match fitness after missing the start of the season with injury.
Whichever way Bennett goes, Niu's replacement will have big shoes to fill, with the Tongan representative and ex-Bronco scoring a hat-trick against the Newcastle Knights a fortnight ago, but also averaging 139 metres per game so far this year, while not missing a single tackle across his four games.
Teams for Round 5 will be named at 4pm (AEDT) on Tuesday afternoon.