The castle was built by the Normans around 1200 AD, and was occupied by them until c. 1350, when the Mac Aodhagáin (MacEgan, Egan, Keegan) were installed on the lands.
The castle was enlarged and renovated several times, with considerable work from 1350. Aside from the original thick stone walls, the building demonstrates some architectural features common to Irish fortifications of the period (including a murder-hole), and some less common features (including a Sheela na gig).
The castle remained under continuous occupation and ownership by the (Mac)Egan families until it was confiscated and burned at the time of the Cromwellian conquest c.1650.
The site remained in ruin for over 300 years, with only the thick exterior walls standing, until Michael J. Egan, a Mayo lawyer, purchased and renovated the building in 1972. While the castle remains a private residence, terms of the Department of Finance Heritage/Cultural Tax Relief mean the castle is periodically open to the public during the summer months. It is a protected structure (ref S329) on the North Tipperary list of protected structures.
The castle hosted several "Clan Egan" rallies in 2000, 2004 and 2008.
- "Official Irish Tourist Board website - Redwood Castle". DiscoverIreland.ie. Fáilte Ireland. Retrieved 10 December 2016.
- "History of Redwood Castle". Redwoodcastleireland.com. Retrieved 10 December 2016.
- "Redwood (Redwood Castle, Co. Tipperary)". Ireland's Sheela na Gigs. Retrieved 10 December 2016.
- "Heritage - Register of Protected Structures" (PDF). Tipperary County Council. Retrieved 10 December 2016.
- "Clan Egan Rallies". Clan Egan website. Archived from the original on 18 August 2012.