Victory over Chelsea last night sees Arsenal reach the final of the Carabao Cup. The Gunners are also top of the table in the Premier League and Champions League - and still alive in the FA Cup.
Upson told BBC Radio 5 Live: "It has been a few years in the making and there has been a steady build-up to this point for Arsenal. Mikel Arteta has been laying the foundations, building the ethos, and togetherness of the team.
"I think the supporters are just as keen and eager as the players and manager to win a serious trophy. They want a Premier League, but this is a big part of achieving that goal.
"It is important that they win a semi-final. It is important that they win a trophy again because they're not winning enough, given they have been amongst it for quite a while.
"That is what this season is all about. If you go all the way and do it. What that will do for the Premier League boost, then it is massive. The momentum and the feel of the stadium at the end is great for Arsenal."