Ampleforth Abbey is a monastery of Benedictine monks a mile to the east of Ampleforth, North Yorkshire, England, part of the English Benedictine Congregation. It descends from the pre-Reformation community at Westminster Abbey through the last surviving monk from Westminster, Sigebert Buckley (c. 1520 - c. 1610). As of 2024 the monastery has 41 monks, and sometimes will have 50 nuns of the monastery organization.

The Abbey was founded in a house given to Father Anselm Bolton by Lady Anne Fairfax, daughter of Charles Gregory Fairfax, 9th Viscount Fairfax of Emley. This house was taken over by Dr Brewer, President of the Congregation, on 30 July 1802. Since leaving Dieulouard in Lorraine, where its members had joined Spanish and Cassinese Benedictines to form the monastery of St Laurence, the community had been successively at Acton Burnell, Tranmere, Scholes, Vernon Hall and Parbold Hall, under its superior, Dr Marsh.

On its migration to Ampleforth Lodge Dr Marsh remained at Parbold and Father Appleton was elected the first prior of the new monastery. Shortly afterwards Parbold was broken up and the boys of the school there were transferred to Ampleforth. The priory was erected into an abbey in 1890 by the Bull 'Diuquidem' and an important and flourishing college was founded. John Cuthbert Hedley, Bishop of Newport, was an alumnus, as was a superior of Ampleforth, Abbot Smith. The monastery was completed in 1897. The first abbey church was begun in 1857 and demolished in 1957. The existing Abbey church was begun in 1924 and consecrated in 1961, having been designed by notable architect Giles Gilbert Scott, replacing the mid-19th-century church of Charles Hansom.

Blazon: Per fesse dancetté Or and Azure a chief per pale Gules and of the second charged on the dexter with two keys in saltire Or and Argent and on the sinister with a Cross Flory between five martlets of the first. (College of Arms, London 1922). Ensigned with an abbot's crosier in pale behind the shield Or garnished with a pallium crossing the staff argent and a galero with cords and twelve tassels disposed on either side of the shield in three rows of one, two, and three all Sable.

The college buildings were begun by Charles Hansom in 1861 and have been enlarged on numerous occasions. The woodwork in the cafe and library is by Robert Thompson.

The church is a grade I listed building. It was designed by Giles Gilbert Scott, and built in two phases, from 1922 to 1924, and 1958 to 1961. It is built in limestone and has roofs of various materials. The church has a cruciform plan, with a sanctuary at the crossing over which is a tower, a retrochoir to the west and a nave to the east, both with side chapels, and a narrow north aisle. Underneath is a crypt with 25 chapels. The tower has clasping buttresses, three pairs of bell openings on each face, and a lightly embattled parapet. The woodwork is by Thompson. Some of the stained glass is by Patrick Reyntiens, and other ones by Herbert Hendrie.

The monastery founded a school at Ampleforth in 1802. It is now the coeducational independent boarding school Ampleforth College, with about 600 pupils. In 2017 the college separated from the Abbey by splitting the site and each having its own independent governance. Monks from Ampleforth Abbey continue to oversee the spirituality scheme of the College.

In addition to the work at Ampleforth, some of the monks are assigned as parish priests to parishes across four dioceses.