Thomas Andrews was born on December 19, 1813, in Belfast, Ireland, the son of a Belfast linen merchant.

He was an Irish chemist, physicist, and professor. He attended the Belfast Academy and the Royal Belfast Academical Institution, where he studied mathematics. He continued his studies at the University of Glasgow (chemistry), Trinity College, Dublin (classics and science), and the University of Edinburgh (M.D., 1935). Andrews began a successful medical practice in his native Belfast in 1835, also giving instruction in chemistry at the Academical Institution. In 1845, he was appointed Vice-President of the newly established Queen's University of Belfast and its first Professor of Chemistry. He held these two offices until his retirement in 1879. An outstanding experimentalist, he was the first to show that ozone is another form of oxygen. In 1844, the Royal Society awarded him a Royal Medal for his research into gases. In 1867, became president of the British Association for the Advancement of Science.

In 1842, he married Jane Hardie Walker (1818–1899). He died on November 26, 1885, in Belfast, Ireland.