[1] Born in Faicchio, he was brother of Angelo, professor first of medical physics then of mathematics at the University of Naples; and of Nicola Antonio De Martino, professor di mathematics and director of the Real Corpo degli Ingegneri (Royal Engineers Corp) and Marine Guard.
Pietro De Martino was a pupil of Agostino Ariani and of Giacinto De Cristoforo (1650-1730).
In 1735 he was assigned of the astronomical and nautical chair at the University of Naples.
[2] He disputed with Roger Joseph Boscovich on the question if it is possible to gain a right result starting from a wrong hypothesis.
[1] He authored various works; his Nuove istituzioni di aritmetica pratica, published originally in 1739 in Naples, had many reprints (the better known of the 1758; one also in Turin in 1762).