The Giants and cornerback Adoree’ Jackson waited to reunite until neither side could deny that it was in their mutual best interest.

Jackson, 28, is re-signing a one-year deal to return to the Giants for a fourth season, The Post confirmed.

He has been without a team since free agency opened in March but was called into his old home Friday morning for a physical.

The Giants tried moving on from Jackson, but they didn’t add a cornerback in free agency who survived the 53-man cut down.

And their plans to draft one in the second round were spoiled when Kool-Aid McKinstry (Saints) and Kamari Lassiter (Texans) were picked before their turn.

Neither Cor’Dale Flott nor Nick McCloud seized the job vacated by Jackson as the outside starter opposite Deonte Banks.

Whether Jackson steps right back into the lineup by Sept. 8 against the Vikings or is eased into a rotation will be determined on the practice field.