Montézin was born in Paris in 1874, to a lace designer. After ten years of rejection, in 1903 Montézin finally had a work accepted by the Salon. When war broke out in 1914, Montézin enlisted and fought at the front, receiving the Médaille Militaire after the battles of the Meuse. At the end of the war, he resumed his painting in the quiet village of Dreux where he produced a good number of landscapes and began exhibiting at the Salon des Artistes Français.
He received the Rosa Bonheur Prize in 1920 and in 1923 he was named Chevalier de la Legion d’honneur. In 1932 he obtained the Medal of Honour at the Salon des Artistes Français for a landscape painting, the first artist to do so since 1897. In the same year Montèzin was elected president of the Salon jury, and he had a large and important exhibition in Paris which was a popular success. Similarly successful exhibitions in Paris followed in 1936, 1938 and 1943. Montèzin painted to the end of his life, dying suddenly in 1946 during a trip to Brittany.