Two second half goals from Rob Hopley secured the victory, the second of them coming from a great cross by Williams who did well when he came on for his debut after half-time.
The 19-year-old Caernarfon-based winger, who was with Caernarfon Town and Chester last season, has been training with FC United and was also interesting Southport, but Bay’s head of recruitment Phil Staley has convinced him to join the Seagulls.
He has also had a spell at Hereford United as a youth and had a trial with Premiership club Swansea.
Manager Ash Hoskin said he was the type of player he has been looking for to take on full backs down the flank
“He gives us width, gets in good crosses and tracks back well to help his full back,” said Hoskin.
“He did well when he came on but I thought the whole team were excellent in the second half and that is the best we’ve been to date.
“We managed the game very well, particularly after we scored the first goal because it was massive that we didn’t concede a quick equaliser like we did against Bangor and Bala.
“We grew in confidence after that. John Dillon was outstanding and ran the game in midfield and that is what I want him to do.
“I am relieved to have got the first win because that is burden off my back, but most of all I was delighted with that performance in the second half against a good Llandudno side.
“They were the better side first half when we weren’t strong enough off the ball, but we had a good discussion at half-time and were much better after that.”
Llandudno certainly started the game the better, with former Seagulls skipper Marc Williams prominent in midfield, and only a tremendous reflex save by Chris Sanna prevented a Danny Hughes header giving the home side the lead.
Later Gaz Evans missed a good chance by shooting over the bar after being set up perfectly by Lewis Buckley, but Colwyn Bay came more into the game in the latter stages, with Sam Barnes and Luke Denson doing well as a central defensive partnership in the absence of injured Jordan Fagbola.
They should have taken the lead before half-time, only for Harry Clayton to some how head wide at the far post from less than a yard out.
The second half saw the Seagulls start to dominate and they took the lead on 61 minutes when home keeper Paul Roberts could only parry a Robbie Booth free kick and Hopley scored from close range.
Hopley slid into score his second 15 minutes later from Cory Williams’ penetrating right wing cross.
Luke Denson had a header tipped over the bar and Damian Ketley saw another header cleared off the line as Bay pressed for a third goal, although it needed another good save by Sanna to deny Llandudno’s Lewis Moynes a goal at the other end.
The Seagulls used 17 players on the night.
The squad on duty were: Sanna, Baynes, Corbett, Dillon, Barnes, Denson, Booth, Dowling, Rodgers, Sharp Clayton, Rees, Hopley, Love, Ketley, Williams, Zibaka, Holt.