The Leinster duo picked up injuries in the second half of their country's 22-19 defeat to the All Blacks in Christchurch on Sunday.
Inside centre D'Arcy left the field during the game due to injury and following a scan, it revealed a calf strain and he will be unavailable for the final test.
The 32-year-old had been recalled to the Test side following the shoulder injury sustained by Keith Earls in the first Test.
D'Arcy will return home and Ulster centre Paddy Wallace has been called into the squad as cover. He will arrive in New Zealand on Tuesday.
Heaslip, Ireland's Number 8 in the first two Tests of the series, damaged his finger during the match at the AMI Stadium but played out the entire 80 minutes.
The finger was x-rayed after the game and showed a fracture of Heaslip's right index finger.
This will rule him out of this weekend, but with the options available within the squad, no replacement has been called for.