The Sky Blues moved a step closer to a first major trophy success in 21 years when they finally saw off the stubborn resistance of Glenavon in their JJB Sports Irish Cup quarter-final replay.
Second half goals from Andy Smith and Noel Anderson took the Sky Blues into a semi-final clash with Portadown on April 10.
"I think when you look at the games, and it took us two goes at it, I don't think anybody could argue that we deserve to go through," Walker told Times Sport.
"I was disappointed with our first half – lack-lustre might be a bit strong but there seemed to be a bit of a carry-over from Saturday.
"At half-time we told the players they would have to pass the ball a bit better and we thought our midfielders were sitting on top of our defenders.
"I genuinely thought some of our play in the second half was excellent and it was a fantastic goal by Andy. He deserved it for his work-rate over the two games.
"We would have been disappointed if we hadn't gone through but the players were ecstatic," added Walker.
The replay failed to reach the same thrilling heights as Saturday's 3-3 draw in the sides' first meeting, with few really clear-cut chances in the opening half.
Glenavon bossed the early stages of the second period and King's cross-shot fell at the feet of Willo McDonagh who screwed his shot badly wide from eight yards.
Shortly afterwards, the mercurial Molloy, spotting Dwayne Nelson off his line, tried his luck from just inside the Ballymena half and the back-pedalling goalkeeper was relieved to see the ball drift wide.
Ballymena spurned a gilt-edged opening on 62 minutes when Aaron Stewart beautifully floated a cross behind the defence but Michael Smith could not force the ball past Andrew Plummer from close range.
But two minutes later, United went in front through Andy Smith. The former Northern Ireland striker evaded a Jay Magee challenge and exchanged a one-two with Kevin Kelbie before firing a crisp finish across Plummer and into the bottom left hand corner from the edge of the penalty area.
Glenavon threw the proverbial kitchen sink at United in the closing stages and it required a stunning save by Nelson to maintain Ballymena's lead. Eamon Murray's mishit shot dropped at the feet of Shea Campbell and as he tried to place a shot into the far corner, Nelson stretched out a hand to somehow divert the ball behind for a corner.
And Ballymena put the game beyond the Lurgan Blues in the 89th minute through Noel Anderson. The substitute collected the ball in the centre circle and as he looked for options in front of him, he instead strode through a gaping chasm in the Glenavon defence and drilled a low shot past Plummer from the edge of the penalty area.
Ballymena United: Nelson, Ramsey, Stewart, Haveron, Surgenor, Watson, M Smith, Taggart (sub Anderson 83), A Smith, Kelbie, Colligan. Subs: McConnell, Cushley, McNeill, O'Neill.
Glenavon: Plummer, Haughey, Magee, Gracey, Carvill (sub Campbell 78), Molloy, McDonagh, Johnston (sub Harper 80), King, Costello, Liggett (sub Murray 72). Subs: Turkington, Finlay.
Referee: David Malcolm (Bangor).