He was born a member of the Han Chinese Bordered Yellow Banner and had extensive military experience on the western frontier of the Qing Empire.

In March 1709, the Banner company to which the Nian family belonged was assigned to serve the prince Yinzhen, who later became the Yongzheng Emperor.

As General Who Secures the West (定西將軍), Nian Gengyao took an active part in supplying Yinti's campaign in Tibet against Tsewang Rabtan.

In June 1721, he was granted an audience with the elderly Kangxi Emperor at Rehe and subsequently raised to the rank of Governor-General of Sichuan and Shaanxi.

When Nian made a visit to Beijing in late 1724, and paid his respects to the Yongzheng Emperor, he was given additional honours and privileges normally granted to a Prince of the First Rank.

Nian himself was not slow to discover that he had lost imperial favour, for on his return to Xi'an in January 1725 he submitted a memorial of his own, protesting his loyalty and imploring the Yongzheng Emperor's mercy.