The latest deals make it 10 current players who have committed their future to Connacht in recent months.
22-year-old O'Halloran has penned a two-year deal with his home province. Starting on the wing in the win against Edinburgh at the weekend, he marked his 61st Connacht cap since making his debut against the Scarlets in the 2009/10 season.
A product of the Connacht Academy, the Connemara native holds the honour of scoring Connacht's first ever Heineken Cup try away to Harlequins in 2011. O'Halloran has represented Ireland at U18, U19 and U20's level and last summer travelled with the Emerging Ireland squad to play in the IRB Tbilisi Cup.
Outside half Nikora has agreed terms on a new one year contract to remain at the Sportsground.
The New Zealand born 28-year-old joined Connacht in 2009 and has clocked up 66 appearances for the province. A shoulder injury in the summer has kept Nikora out of action this season but the veteran Number 10 returned to start for the Connacht Eagles this month and played for AIL side Corinthians RFC in their bonus point win over Blackrock RFC at the weekend.
21-year-old local talent Carty will graduate from the Connacht Academy to a one-year professional contract next season. The Athlone-native, who is in his third season in the Academy under Nigel Carolan, captained the Connacht Eagles in the British & Irish Cup this season. With a handful of senior caps under his belt, Carty earned his first start against Leinster in early January. A week later, he played his first Heineken Cup game against Italian side Zebre.
Commenting on the recent re-signings, Head Coach Pat Lam said:
"We are very pleased that Tiernan, Miah and Jack will all be with us next season and all have a significant role to play. Miah has endured a tough year with injury but will be desperate to make up for lost time. Tiernan and Jack are both proud Connacht-born players and testament to the young talent we have here. Both have shown that they have what it takes to make a real contribution to the squad and they will no doubt build on the good work done this season."
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland