The South African-born left-hander topped the scoring in all three formats this season.
It was thought the 28-year-old would become eligible for his adopted country in September. However, the ICC has confirmed he would be available for international selection from August 28.
He has also been granted an exceptional circumstance dispensation by the ICC, which means, should he be selected for the New Zealand A tour of India (starting August 15) or the Black Caps tour of Bangladesh (starting August 12), he will be allowed to play in tour matches before the August 28 deadline.
Conway has carved out a wonderful first-class record. He has scored 6674 runs at an average of 47 in 103 matches, including 17 centuries.
He has a high score of 327 not out and his one-day and twenty20 domestic records are every bit as impressive.
How he fits into a full-strength Black Caps line-up is unclear. But his talent would command a spot.
- Meanwhile, Auckland white-ball skipper Craig Cachopa has called time on his domestic career.
The 28-year-old leaves the game on a high, having led the Aces to two finals this summer, including a memorable triumph in the one-day tournament against Otago.
Cachopa made 47 first-class, 88 list-A and 102 T20 appearances since his domestic debut in 2011.
