The 'Bleeding Love' singer - who was discovered by the music mogul and was signed to his SyCo/Sony label after winning 'The X Factor' in 2006 - has revealed there are no hard feelings between the pair after she brokered her new multi-year deal with Island Records behind his back.
She told The Mirror newspaper: ''I was offered another deal with Syco but I thought it was time to have a new team with fresh ideas.
''I have spoken to Simon. He is sad I didn't stay with Sony but he is happy for me and proud.
''He has been so supportive and he will continue to be supportive and I can always call him up for advice.''
She added: ''It is like leaving home almost. You have to be like, 'Later, mum and dad'. I am doing my own thing now. ''They have given me a great launch pad and I felt it was time for something different - a new phase. Now I'm able to spread my wings, fly and make something for myself.''
Although rumours emerged that Simon, 54, felt snubbed by the 29-year-old singer, he previously took to Twitter to congratulate her on her new contract and thanked her for for putting 'The X Factor' ''on the map''.
He wrote on the social networking site on earlier this month (03.06.14): ''Congratulations Leona. We had 7 great years together and now wish you all the best for the future. You put X Factor on the map. X (sic)''
Take a look back at October's inaugural event.
The film is expected to continue without Mendes' involvement.