Senator Sumulong was born in Antipolo, Rizal on December 27, 1874 to Policarpio Sumulong and Arcadia Marquez.
After finishing his elementary education in his hometown, he went to Manila and enrolled at the San Juan de Letran College and completed his Bachelor of Arts. He acquired Bachelor of Laws at the University of Sto. Tomas and passed the bar examinations in 1901.
After passing the bar examinations, he practiced Law and at the same time taught Constitutional Law at the Escuela de Derecho.
In 1906 he was appointed Judge of the Court of First Instance and the Court of Land Registration in 1908. He was also a member of the Philippine Commission from 1909 to 1913. He ran for, and lost, the position of Senator for so many times and finally in 1925, he was elected to a six-year term as Senator for the fourth district composed of Manila, Rizal, Laguna and Bataan, and also in 1934 elections.
As a Senator, he had his famous debate with Senate President Manuel L. Quezon on the amendment to the Corporation Law. He also voiced out his vehement opposition to the enactment of the Belo Act, giving the governor-general a yearly appropriation fund for military and technical advisers known as the Belo Boys.
He married Maria Salome Sumulong, a distant cousin, with whom he had eleven children, four of them died, and seven survived.