Senator Primicias was born on September 14, 1901 in Alcala, Pangasinan.
He completed his elementary and higschool courses with honors and passed the government first grade civil service tests when he was still in Highschool in 1919. He enrolled in the National Law College and at the same time worked as a clerk in the Bureau of Commerce in 1919 where he rose to the rank of Chief, Commercial Section until 1924 and finished his Bachelor of Laws degree in 1923 and passed the bar examinations at the same year.
In 1924, he quit his post at the Bureau of Commerce and began his law practice as assistant attorney in the law office of Senator Alejo Mabanag.
He entered politics when he was elected as representative for the fourth district of Pangasinan for three consective terms in 1934, 1941 and 1946 elections and he was an oppositionist and fiscalizer in the House of Representatives. In 1951, he was elected Senator and became Senate Majority Floor Leader and chairman of the committee on Rules and the member of the Senate Electoral Tribunal.
Senator Primicias was the former Dean of the College of Law in Orient College, President of the Pindangan Agricultural Company and the Lingayen Gulf Fishing Company and was a member of the Knights of Columbus.