Mikhail Mikhailovich Ustinov came from a noble noble family, founded by the Saratov merchant Mikhail Andrianovich Ustinov (1755, 1836), and was a descendant of his younger son, Mikhail Grigorievich. Mikhail's father, after being discharged from the army in 1857 due to health reasons, lived abroad for a long time. His mother, a Frenchwoman, died shortly after giving birth to the children (according to various sources, in 1860 or 1862). Mikhail had a twin sister, Lydia.

At the age of fifteen, Mikhail was sent to the Saint Petersburg Naval Cadet Corps, which he graduated from in 1882, beginning his service in the Baltic Fleet. In 1890, he transferred to the Ministry of Foreign Affairs and in 1893 received his first overseas appointment as vice-consul in the Japanese city of Hakodate. By 1898, he was already serving as the Russian consul in Nagasaki, and in 1899, in Hong Kong. In 1903, Ustinov was appointed to Melbourne, where he became the first consul general of the Russian Empire in Australia and New Zealand after the consulate was upgraded to a general consulate.

During his service in Melbourne, the Russo-Japanese War broke out, and the Hull Incident occurred, which exacerbated the already tense relations between Russia and England. In late October 1904, ships of the Russian squadron under the command of Vice Admiral Z. P. Rozhestvensky shelled English fishing vessels in the North Sea, near Hull, mistaking them for Japanese destroyers. Mikhail Ustinov wrote: "...the last regrettable incident in the North Sea has completely clouded any sense of measure, and the newspaper reviews, if that is possible, have become even more venomous... Our army and navy are being bombarded with all sorts of slanders, in a word, everything is being done to discredit Russia." One of his main tasks during this period was to monitor the shipment of strategic cargoes from Australian ports. His three-year service in Australia ended in May 1906.

After that, Ustinov served as consul in Lisbon, then in Montreal, and in September 1913 was transferred to a similar position in New York. After 1917, some Russian consuls in the USA and Canada remained loyal to the tsar, including Ustinov, who became the right-hand man of the new ambassador of the Provisional Government in the USA, B. A. Bakhmetev.

In July 1929, Mikhail Ustinov informed the State Department of his departure from the USA to Europe, likely to Paris, where his grandson Adrian Platonovich Ustinov lived. Mikhail Mikhailovich Ustinov passed away on May 5, 1942, in the town of Waterloo.