The Jobstown bantamweight saw his initial debut date in April scrapped and had to wait until the ‘Celtic Clash 3: Building Champions’ card at the National Stadium to make his pro bow.
The Tallaght 32 year old took on Bulgarian Georgi Andonov over four rounds at the home of Irish boxing and put on an extremely impressive display.
The same opponent had gone the distance with another Jobstown fighter, Carl McDonald, back on Celtic Clash 2 in May
McDonagh came roaring out of the gate, attacking the body with vigour and bullying Andonov around the ring.
The Bulgarian had no answer to the sheer volume coming from McDonagh into the second round as he refused to let the pace drop.
A well-timed right staggered Andonov in the third, and the journeyman began to hold and spoil.
McDonagh continued his body assaults in the fourth and final round and almost sent Andonov through the ropes in the closing seconds, but the Bulgarian managed to see the bell.
Going to the card, McDonagh was unsurprisingly awarded the fight on a 40:36 scoreline.
The win sees McDonagh start off at 1(0)-0, while the iron-ribbed Andonov slips to 3(1)-5(0)