The Magpies surprised many last year by finishing fifth in the Premier League, above Champions League winners Chelsea, and earned a place in the Europa League.
After keeping all their players during the transfer window, the full-back believes that the club can now push on and try to finish in the top four.
"Now the transfer window is finished we are relaxed. We have a really good team and can try to win every game because we have that quality," said Santon.
"I don't know where we can go but I think we have a possibility of qualifying for the Champions League this year. If we have the right mentality in every game, why not? We have the quality to do that.
"I think we can cope with the Europa League. It is tough for us and we do not have an easy group but it's important for us in every game to get a win."
The Tyneside outfit will come up against French side Bordeaux, Club Brugge of Belgium and Portugese outsiders Maritimo in Group D of the Europa League.