Defenders Reid, 26, and Taggart, 20, will fight it out for the right-back slot while 36-year-old Hardie, who has impressed in pre-season, brings a wealth of experience in the centre of midfield.
The trio have all put pen to paper on one-year deals to tie them to the Ton for the forthcoming 2012/13 season.
Speaking exclusively to the Tele yesterday, Moore confirmed the hat-trick of signings and told of his excitement at how his squad is shaping up for the new campaign.
He beamed: "We signed Craig Reid, Martin Hardie and Scott Taggart over the weekend, so we're getting there now.
"We had agreed terms with Craig for a wee while.
"He and Martin Hardie passed their medicals at the end of last week before officially signing their contracts at the weekend.
"A lot of our signings have been young, in their early 20s, so it was important to add a few older heads to that to get the right mix of youth and experience.
"I think we've done that by bringing in Mark McLaughlin and now Martin. Martin is 36 and a leader on the park.
"He's a strong character and that was something we were keen to add to the dressing room as we maybe missed that at times last season.
"Craig and the boy Taggart are athletes.
"They've both got pace to burn and will get up and down the right side and get plenty of crosses over. That's what we're looking for from our full-backs.
"They'll be competing with each other for the right-back position. That sort of competition is something we're looking to have across the squad.
"Last season, we'd lose someone to injury and worry about having to fit someone else in, moving right-backs to left-back and looking for cover for Ross Forsyth. This year, we're putting a squad together that has strength in depth.
"Players will be looking over their shoulders and being pushed to make sure they keep their place in the team."
The new additions bring Moore's summer signing tally up to 11.
However, the Ton boss is still on the lookout for another central midfielder, a striker and a central defender.
A new centre-half, he admits, is his most pressing concern, particularly with McLaughlin suspended for the first three games of the season.
He added: "We're very pleased with how things are shaping up, but we know we have to get it right this year.
"So we're still looking for a few more players to complete our squad. We still have a space open for another striker, and we'll be taking a look at a boy from England.
"He's been recommended by former Morton defender Joe McLaughlin, so we'll give him a run out against Kilmarnock.
"Depending on the budget, we might try to add another central midfielder.
"Kyle Wilkie impressed against Concordia. He buzzed about and gives something different. He's someone we're still looking at.
"Ross Forbes went out to Romania last week. He got an offer out there. I've known Ross since he was a young lad and was a neighbour of mine. I've told him we won't be diving in and will keep things open - but the budget can only go so far.
"Kevin Rutkiewicz played against Concordia too and we're hoping he'll play against Kilmarnock.
"He's a quality defender and one we'd like to sign but his situation isn't clear cut at the moment.
"We're certainly looking for another central defender, but I've said to Craig Reid that he might need to play at centre-half in the first three games with Marko out.
"He's played there, and as a sweeper, for Queen of the South, and every time we played them he was their best defender, to be honest."
And Moore revealed that he could even play Reid as a centre-back in tonight's pre-season friendly with Kilmarnock.
He said: "Kevin Rutkiewicz hasn't been feeling great over the weekend and might not be able to play tomorrow, so Craig could play there with Scott Taggart at right-back.
"We'll be using the game to work on our shape, and we'll be looking to play our signed players in order to do that.
"We'll be working on a few different formations. I'll probably try out a 4-4-1-1 and 4-3-3 to see how we get on