Reginald Theodore Blomfield was born at Bow Vicarage, Exeter, Devon, on 20 December 1856, the son of the Rev John Blomfield and grandson - through his mother - of Charles James Blomfield, Bishop of London. He was brought up in Dartford, Kent where his father was appointed Rector, and from 1868 at Aldington, also in Kent. He was sent to Haileybury as a boarder in 1869 and from there he went to Exeter College, Oxford, where he read Classics and graduated MA. In 1880, after a tour of the continent, he was articled to his uncle Arthur William Blomfield and entered the Royal Academy Schools, where he was more influenced by the visiting academicians Richard Norman Shaw and George Frederick Bodley than he was by his uncle whom he left as a result of 'a misunderstanding' after only two years. He was admitted ARIBA as early as 1881, his proposers being Philip Charles Hardwick, Alfred Waterhouse and his Blomfield uncle. In 1884 he set up independent practice at 17 Southampton Street, Strand, where Edward Schroeder Prior also had his office. Through Prior Blomfield met Mervyn Macartney, William Richard Lethaby, Ernest Newton and Gerald Horsley, becoming a member of the Art Workers' Guild and the Arts & Crafts Exhibition Society. In 1886 he married the daughter of Henry Burra of Rye, Sussex, who commissioned him to build several houses, one of which was let to Henry James, and in 1890 he was one of the founders of Kenton & Company in association with Macartney, Lethaby, Ernest Gimson and Sydney Barnsley.
In the 1880s Blomfield began his parallel career as an architectural illustrator and writer, initially in journals. He published his first book, 'Formal Gardens in England', in 1892, followed by 'A History of Renaissance Architecture in England', The first of these led to his one major Scottish commission, the terraces and formal gardens at Mellerstain, and the second publicised his name as an architect for country house restoration work and for new houses in a fairly convincing late Stuart-early Georgian manner. These together with the Sherborne School for Girls (1902), the United Universities Club in Pall Mall, London (1907-10) and Lady Margaret Hall in Oxford, brought election as Associate of the Royal Academy in 1905, re-admission to the RIBA in 1906 as a Fellow with John Belcher and Aston Webb as his proposers, and appointment as Professor of Architecture at the Royal Academy in 1907, an honour he held until 1911. In that year Blomfield began publishing his greatest literary work, 'A History of French Architecture 1494-1661', the studies for which strongly influenced his later designs.
Although he had been re-admitted as a Fellow for only six years, Blomfield was elected President of the RIBA in 1912 and was somewhat controversially Royal Gold Medallist in 1913 during the period of his tenure. The award of the Legion d'Honneur in May 1914 was blocked by the Foreign Office, and in that same year Blomfield suffered a serious breakdown in health brought about by over-work and, perhaps, annoyance; he recuperated on Sir George Warrender's flagship at Weymouth.
Blomfield was appointed one of the three principal architects to the War Graves Commission in 1918. In addition to the Menin Gate at Ypres, he designed the War Cross, a standard feature of all British war cemeteries. He was knighted in 1919, and continued practice into his old age with his son Austin Blomfield, born 1892. His last years were highly controversial with a bitterly opposed proposal to replace Nash's Carlton House Terrace in 1933 and an attack on all modern movement architecture, 'Modernismus', published in 1934.
Blomfield died in Hampstead on 27 December 1942.