Ozil had been linked with a move away as he was entering the final few months of his present deal but he has signed a renewal that keeps him at the club until 2021.
Reports claim he will be the highest ever paid player at the club with his new deal which keeps him in north London but Bellerin says he was always confident the former Real Madrid playmaker would stay.
“Everyone in the training ground, everyone in the team knew he was going to stay,” Bellerin told the club’s official website.
“He is a guy that loves London, loves Arsenal and he always gets really angry when things don’t go well, so you know how much it means for him to win or lose for this club.
“So I think everyone in the club, the dressing room, was sure.
“It is as exciting as a new signing. To have a player with Mesut’s qualities and all he brings to the team to sign for a few more years, it is really exciting for Arsenal and for the fans.”
Uwe Rosler was sacked by Fleetwood following a 3-0 reverse at Doncaster which condemned Town to a seventh straight defeat in all competitions.
Cambridge interim head coach Joe Dunne was pleased with how his side adapted to beat Grimsby 3-1.
Southend manager Chris Powell led the applause for Jason Demetriou after the right-back scored twice in the 3-1 win against Portsmouth at Roots Hall.
Morecambe boss Jim Bentley was the happier manager after Gregg Wylde's 90th-minute strike earned his side a point in their 1-1 draw with Forest Green.
Manager Gareth Ainsworth described Wycombe's 2-0 win at Cheltenham as a thoroughly professional performance.
Skipper Richard Wood scored the winner just before half time as in-form Rotherham pulled off a 1-0 victory at League One leaders Shrewsbury.