Marcolongo graduated in 1886, and later he was an assistant of Valentino Cerruti in Rome.
He worked on vector calculus together with Cesare Burali-Forti, which was then known as "Italian notation".
In 1906 he wrote an early work which used the four-dimensional formalism to account for relativistic invariance under Lorentz transformations.
In 1921 he published to Messina one of the first treaties on the special relativity and general, where he used the absolute differential calculus without coordinates, developed with Burali-Forti, as opposed to the absolute differential calculus with coordinates of Tullio Levi-Civita and Gregorio Ricci-Curbastro.
He was a member of the Accademia dei Lincei and other Italian academies.