Ettore Bortolotti studied in Bologna, graduating in 1889. He became an assistant there and worked at Bologna until 1891. In that year he was appointed to the Lyceum of Modica in Sicily. From 1892 he undertook postgraduate studies at Paris then, in 1893, he was appointed to the University of Rome and taught in Rome until 1900 when he became professor of infinitesimal calculus at Modena. His teaching at Modena at this time included analysis and rational mechanics.
Bortolotti was Dean of the Faculty at Modena in 1913-14, then he was appointed professor of geometry at the University of Bologna where he remained for the rest of his life, retiring in 1936.
Bortolotti studied topology at first but later went in the direction of analysis considering the calculus of finite differences, continued fractions, convergence of infinite algorithms, summation of series, the asymptotic behaviour of series and improper integrals.
He was always interested in the history of mathematics studying Ruffini's manuscripts while at Modena, then later editing Ruffini's Complete Works. He also studied Torricelli's calculus results and he vindicated Cataldi's claim to have discovered continued fractions. Bortolotti also studied Fibonacci, del Ferro, Tartaglia, Cardan, Ferrari.
In 1929 Bortolotti published the ly lost work of Books 4 and 5 of Bombelli's Algebra.