Madog belonged to a junior branch of the House of Aberffraw and was a distant relation of Llywelyn ap Gruffudd, the last recognised native Prince of Wales.

[1] His eldest son, Madog, who may have been born in exile, is known to have received substantial monetary gifts from King Edward I of England in 1277, and used this money to sue the Prince of Wales in 1278 in an attempt to have his father's cantref of Meirionydd returned to him.

It appears that Madog returned to Gwynedd after the death of Llywelyn ap Gruffudd in 1282, and received lands from the King of England in Anglesey.

[2] On Michaelmas (29 September) 1294, Madog put himself at the head of a national revolt in response to the actions of new royal administrators in north and west Wales and the imposition of taxes such as that levied on one fifteenth of all movables.

However, due to bad weather Edward's army had not yet sailed and he quickly cancelled the French campaign to deal with the Welsh uprising.

In December 1294 King Edward led an army into north Wales to quell the revolt, stopping at Wrexham, Denbigh, Abergele, and elsewhere on his way to Conwy Castle, which he reached shortly before Christmas.

[8] Madog barely escaped from this episode with his life and was a fugitive until his capture by Ynyr Fychan of Nannau and hand over to John de Havering in Snowdonia in late July or early August 1295.

The revolt of 1294–95 elicited a harsh response from Edward I in the form of humiliating and punitive ordinances further restricting the civil rights and economic and social opportunities of the Welsh.