[1][2] After graduating in 1980, he worked as a postdoctoral research associate with Professor George Wallerstein in the Department of Astronomy at University of Washington.

After moving to Chile in 1986, Suntzeff working with Mark M. Phillips and Mario Hamuy at CTIO used the newly developed cryogenic CCD cameras to produce the first modern light curve of a Type Ia supernova.

The Survey, formed after discussions at the Santa Cruz meeting on supernovae[6] and the encouragement by Allan R. Sandage to use Type Ia supernovae to measure the Hubble constant H0 and the deceleration parameter q0, ran from 1990 to 1995, and provided the pioneering method to measure precision distances to external galaxies,[7] leading to a precise value of the Hubble constant.

"[14] In announcing his award as a 2023 American Astronomical Society Fellow, he was cited "For his transformational leadership in the foundation of supernova cosmology, the discovery of the accelerated expansion of the universe, and precision measurements of the Hubble–Lemaître flow; for his service to the national and international astronomical communities; for considerable efforts on behalf of human rights, especially the LGBTQ community, both within astronomy and globally; and for establishing the astronomy program at Texas A&M University.

He is the paternal grandson of Matvei Andrianovich Evdokimov (1887–1920) (Russian: Матвей Андрианович Евдокимов), one of the principal private arms manufacturers in czarist Russia, located in Izhevsk.

Nicholai assumed the last name of his mother and immigrated into the US as Nicholas Matveevich Suntzeff (Russian: Николай Матвеевич Сунцев).

The Suntzeff family, prominent merchants from the Ural region, came from Motovilikha (now part of Perm, Russia) and have ancestry in the Udmurt people.