Holcomb taught school for a number of years, while studying law in the office of the Hon.

[2] While a judge of Southington's probate court from 1873 to 1910, Holcomb switched from Democratic Party to Republican in 1888.

Connecticut's debt was reduced and a bill was enacted that regulated maximum working hours for women.

Teacher retirement benefits, old-age annuities, and health insurance programs also were instituted.

However he became a storm center when he refused to convene the Connecticut Legislature to act on ratification of women's Suffrage Amendment to the US Constitution because of his personal opposition to it.

The Marcus Holcomb Residence Hall, an all-female dormitory built in 1921 and located on the Storrs campus of the University of Connecticut, was named in his honor.