Robbie Keane scored a hat-trick inside 12 first-half minutes - including the opener after just six minutes - to give the home side a decisive lead in the Aviva Stadium and take his individual tally in international football to 65.
Derry born Wigan winger McClean then got in on the act after the break, scoring either side of goalkeeper Jordan Perez's own goal, and Wes Hoolahan completed the rout with a 56th-minute effort to make it two wins out of two for the Irish in Group D.
McClean told Sky Sports: "We did a professional job, we prepared the right way. It was important to get the early goal and settle everyone down.
"The goals meant everything. Playing for my country is the greatest privilege in football and to score goals, my first home goals as well, it's something that will be with me forever. Hopefully I can push on from that and get a few more.''
Martin O'Neill's men now take their qualifying campaign to Gelsenkirchen and a meeting with world champions Germany on Tuesday night, and McClean knows the importance of having two wins under their belt ahead of that match.
"We've got six points on the board and from the start that was our objective going into Germany," added McClean.
"We're under no illusions that's going to be a really tough ask, but hopefully we can go there and get at least a point.''
