The German international says the in-form Gunners are determined to continue their upward trajectory in 2015 by finishing runners-up behind champions Chelsea and then lifting the FA Cup for the second successive season.
And if they achieve both ambitions Mertesacker reckons it will give the Gunners the confidence to end their 11-year wait for the championship.
He also says that not having to pre-qualify for the Champions League in August will help Arsene Wenger’s team make a fast start to the campaign.
"I think the way we progressed in 2015 is absolutely fantastic,” he said. “Everyone wants to finish strong.
"We want to qualify directly for the Champions League. After the title is gone, that for us would be an improvement from last season where we had two qualifying matches, really tight ones, to secure Champions League football.
"That's the first target and then the FA Cup, to defend that trophy would be really amazing. That's the focus at the minute. It looks like we are quite sharp and the way we are going is really pleasing."
A World Cup hangover and two tough Champions League qualifiers against Turkish club Besiktas hampered Arsenal’s start to the season.
Whereas they took only 17 points from their first 12 League games, Chelsea amassed 32 – and they have never been able to close the gap.
Mertesacker added: "Post World Cup was not good enough, we have to admit that. How we finish season after season is fantastic but we have to be sharp from the start of the season. That is what we lack.
"We dropped 10 or 11 points at the start of the season and we could not close that gap. We also had a couple of horrible injuries over more than three or four months to key players.
"At the moment, we have a good squad. Selecting the squad is quite difficult for the manager at the minute and that is maybe key to that success at the moment because the contribution from every player, even on the bench or the stands, is fantastic. That is the unit we want to build on.
"We have been consistent in 2015 but Chelsea did not drop many points. When we look at ourselves, we feel we have made progress."
Mertesacker says Arsenal are not dwelling on their poor start but instead looking forward to finishing with a flourish and continuing their form next season.
"Are we frustrated by the poor start? That's not our focus. What is at stake is that we want to build on our success in 2015.
"What happened in 2014, maybe we regret that. But our focus at the moment is on having a strong finish and the FA Cup Final. We can talk about opponents or anything else next season, but not now.
"We don't listen too much to what other people say. Our success is built on our unit and how we train every day.
"That is our job, not thinking about what other people think. People have written us off a lot of times this season and we managed to deal with that. That's not our focus."
Arsenal’s hopes of continuing their great form have been boosted by the return of Jack Wilshere whose 22 minutes as a substitute in the 3-1 win at Hull represented his first appearance since suffering an ankle injury in November.
"You can see his contribution is vital,” said Mertesacker. “He can run at the opponents and create some special moments.
"That is what we want to see from him. But we need to give him time to get really sharp and really fit.
"We are pretty much happy with the performance at Hull. It's a massive win for us. They are fighting to avoid relegation, so it was a tough occasion, but how we dealt with it was really pleasing.
"We were a bit lucky at the start as scored two deflected goals. But you need that away from home, a bit of luck, and the third goal was a piece of Arsenal.
"In the second half after we conceded, we kept them away from our goal and that was very convincing defensively. That makes me very happy."
"It's so unpredictable what we are doing [in attack]. Even for me at the back, it sometimes looks a bit weird what we are doing.
"Sometimes we lose the balance, sometimes it's really good, so we have to keep on going and focusing on our game defensively to keep a clean sheet."