The 44-year-old, who coached Eastern Suburbs to their first win of the New Zealand Premiership last year, is a former New Zealand U-17 head coach.
He's a former All Whites captain and played for the national team for 11 years.
Hay said it was a huge honour to become coach.
"I've been heavily invested in the game in this country for a very long time now, and the All Whites in particular is something that is very close to my heart having played for, and captained the side," he said.