The 1888–89 FAW Welsh Cup was the 12th edition of the annual knockout tournament for competitive football teams in Wales.

The competition was won by Bangor.

Source: Welsh Football Data Archive Source: Welsh Football Data Archive Source: Welsh Football Data Archive Source: Welsh Football Data Archive Source: Welsh Football Data Archive Davenham receive a bye to the next round Source: Welsh Football Data Archive Bangor receive a bye to the next round 1 Match protested regarding poor light, re-play was organised 2 Match protested regarding ineligible man, re-play was organised Source: Welsh Football Data Archive 1 match abandoned after poor light Source: Welsh Football Data Archive Source: Welsh Football Data Archive Chirk AAA receive bye to next round 1 match protested, re-play was organised Source: Welsh Football Data Archive Source: Welsh Football Data Archive Source: Welsh Football Data Archive .