An Upper East Side baby was saved from the brink of death Saturday morning — thanks to the hero cop who breathed precious life back into her in the front seat of a speeding police car.

Parents Diana and Jason Schechter burst into tears of joy in the back seat as Officer Michael Konastosis performed four chest compressions and mouth to mouth, and little Norah began breathing again.

“The baby let out a belch, and we were ecstatic — the color started coming back into her face,” Konastosis told The Post.

The police car continued to Cornell Hospital, where Norah, age 15 months, was treated and released.

The parents had called 911 from their East 74th Street home when the baby stopped breathing, and Konastosis — a former EMT — happened to be nearby with partner Officer David Roussine.