The site on which the cathedral stands in the City of Westminster was purchased by the Diocese of Westminster in 1885. Westminster Cathedral is the largest Catholic church in England and Wales and the seat of the Archbishop of Westminster.

In the late 19th century, the Catholic Church’s hierarchy had only recently been restored in England and Wales, and it was in memory of Cardinal Wiseman (who died in 1865, and was the first Archbishop of Westminster from 1850) that the first substantial sum of money was raised for the new cathedral. The land was acquired in 1884 by Wiseman’s successor, Cardinal Manning, having previously been occupied by the second Tothill Fields Bridewell prison.

After two false starts in 1867 (under architect Henry Clutton) and 1892 (architect Baron von Herstel), construction started in 1895 under Manning’s successor, the third archbishop, Cardinal Vaughan, with John Francis Bentley as architect, and built in a style heavily influenced by Byzantine architecture.

The cathedral opened in 1903, a year after Bentley’s death. One of the first public services in the cathedral was Cardinal Vaughan’s requiem; the cardinal died on 19 June 1903. For reasons of economy, the decoration of the interior had hardly been started and still much remained to be completed. Under the laws of the Catholic Church at the time, no place of worship could be consecrated unless free from debt and having its fabric completed. The consecration ceremony took place on 28 June 1910, although the interior was never finished.

The whole building, in the neo-Byzantine style, covers a floor area of about 5,017 square metres; the dominating factor of the scheme, apart from the campanile, being a spacious and uninterrupted nave, 18 metres wide and 70 metres long from the narthex to the sanctuary steps, covered with domical vaulting.

As in all Catholic churches, there are the Stations of the Cross to be found along the outer aisles. The ones at Westminster Cathedral are by the sculptor, Eric Gill, and are considered to be amongst the finest examples of his work.

Despite its relatively short history compared to other English cathedrals, Westminster has a distinguished choral tradition. It has its origin in the shared vision of Cardinal Vaughan, the cathedral’s founder, and Sir Richard Runciman Terry, its inaugural Master of Music. Terry prepared his choristers for a year before their first sung service in public. For the remainder of his tenure (until 1924) he pursued a celebrated revival of great quantities of Latin repertoire from the English Renaissance, most of which had lain unsung ever since the Reformation. Students at the Royal College of Music who would become household names were introduced to their heritage when Charles Villiers Stanford sent them to the cathedral to hear "polyphony for a penny" (the bus fare). This programme also required honing the boys’ sight-reading ability to a then-unprecedented standard.

In 1977, as part of her Silver Jubilee celebrations, Queen Elizabeth II visited the cathedral. Although there was no religious service (the visit was to a flower show) it was highly symbolic as the first visit of a reigning monarch of the United Kingdom to a Catholic church in the nation since the Reformation.

On 28 May 1982, the first day of his six-day pastoral visit to the United Kingdom, Pope John Paul II celebrated Mass in the cathedral.