Munroe, 28 next month, had won the title against Spaniard Kiko Martinez in the same ring eight weeks earlier. But, after surviving a bright start from Bouaita, the result was never in much doubt.
And the Englishman was already well ahead on points when Bouaita failed to answer the call of the bell for the eighth round and stayed rooted to his stool.
Munroe is now being linked with an all-East Midlands clash against Newark's Esham Pickering.
But the current British and former European super-bantamweight champion, 31, must get through next month's title defence against Matthew Marsh in London's York Hall.