The land where modern Llanrumney stands was left to Keynsham Abbey by the Lord of Glamorgan after the Norman Conquest.

[2] According to legend, Llywelyn ap Gruffudd, the final prince of an independent Wales, was interred in a stone coffin by the monks in 1282, on land where Llanrumney Hall would be built centuries later.

It remained in their possession until 1951, when it and its grounds were compulsorily purchased by the local authority in order to build the large estates that can be seen there today.

[4] The origins of the name Llanrumney are found in the Welsh word glan ('bank, shore') and the Anglicised version of Rhymni, the name of the local river.

[5] The district is predominantly composed of large-scale council estates and is bounded by the wards of Pontprennau & Old St. Mellons to the north, Rumney to the south, Penylan to the southwest, and Pentwyn to the west.

Llanrumney Hall, a pub that is reputedly haunted, is one of several local places associated with the pirate Henry Morgan, and is claimed to have been his home from 1635.

In February 2008, Cardiff County Council approved plans for a new Park and Ride facility to be created on the Rhymney River flood plain adjacent to the nearby Pentwyn Interchange of the A48.

The question they were asked to vote on at the ballot box was "Do you agree with Cardiff City and County Council that the new school should be built on the Rumney Recreation Ground/Eastern Leisure Centre Site?"