Mikołaj Sasinowski (16 November 1909 – 6 September 1982) was a Roman Catholic bishop of the Diocese of Łomża from 1970 to 1982.

After his military service, he entered the diocesan seminary in Łomża on 4 October 1931; he was ordained a priest on 28 March 1935 by Stanisław Kostka Łukomski.

In fall 1939, after the outbreak of World War II, he joined the Polish military and underwent an officers' training course at Coëtquidan.

Sasinowski was evacuated to north Africa on 25 June 1940 after the fall of France, and was later transported to the United Kingdom.

[1] On 16 July 1940, Sasinowski was assigned to the 18 Operational Training Unit RAF, based at Hucknall Aerodrome, as well as the No.

[1] After returning to Poland, Sasinowski was appointed vicar and prefect of a secondary school based in Ostrołęka.