Ozil: Ancelotti lacked confidence in me
The Germany international moved to the Emirates Stadium for a club record fee on Monday, partly assuaging the concerns of the club's fans, who were growing restless at the lack of investment in the playing staff.
However, Ozil, whose price tag was reported to be £42 million, had expected to remain at the Santiago Bernabeu before opting for a switch to the Premier League.
"I was certain...that I would stay at Real Madrid," Ozil said in an interview with the German Football Federation.
"Then I realised that I didn't have the confidence of the coach and the officials after all.
"I am a player who needs that confidence and I saw that I would have that at Arsenal and that is why I am going there."
The 24-year-old spent three years at Real following his move from Werder Bremen in 2010.
Ozil revealed that he wants to play regularly under Arsene Wenger to ensure that he features in Joachim Low's Germany squad for the FIFA World Cup.
"Wenger gives me the confidence that I can develop further and I want to be in top form for the World Cup next year," Ozil continued.
"I spoke to him for a long time on the telephone and he told me his expectations and he trusts me, which I need as a player.
"I am a player who always wants to play a whole match, the full 90 minutes.
"I am looking forward to the new challenge. I have already heard that they have fantastic fans, the city is great and the team is of a very high quality."
Ozil was one of four players to leave the Bernabeu on the final day of the transfer window, with Denis Cheryshev moving to Sevilla on loan, Kaka joining Milan and Antonio Adan being released.