No, it was made by Pixar. Disney merely distributed and advertised the film they had no involvement in the making of it.
Up and any other Pixar film will never appear in a list or a timeline of films made by Disney.
Is this pedantry really necessary?
Let alone the fact that I was the THIRD person to mention Disney - which is the only reason I even thought it was 'made' by them.
I don't really care or take note of who makes what, I just know if I like something or not.