The French full-back completed his £5.5million switch from Lille.
But Debuchy, 27, is adamant Alan Pardew's men can start rising the table and challenging for the Champions League again.
He said: "Results may not be great at the moment but I'm not concerned and that didn't influence my decision. I'm confident in the club and what they're doing.
"I'm confident we can come back and soon we'll be climbing the table.
"The Champions League is a target but the first thing is to get Newcastle back up the table. That is the priority now."