The 39-year-old former All Blacks midfield back has been named on East Coast's bench for tomorrow's match against Buller in Ruatōria.
East Coast are coached by 14-test All Black Hosea Gear, who is also poised to make his debut for the province off the bench.
Gear hasn't played a competitive match since 2018.
Their old Hurricanes teammate Faifili Levave has also been named amongst the East Coast reserves.
Nonu, who played 103 tests for the All Blacks before retiring after the 2015 World Cup win over Australia, returned home to New Zealand this year after stints in America and France.
East Coast's last win came against Poverty Bay in September 2013.
Buller, who are also winless four games into this year's Heartland Championship, were supportive of Nonu's inclusion on their Facebook page.
'What an amazing opportunity for our lads to come up against one of the games greats! Awesome for Heartland rugby!!!