"You've Got a Friend in Me" is a song by Randy Newman. Used as the theme song for the 1995 Disney / Pixar animated film Toy Story, it has since become a major musical component for its sequels, Toy Story 2 (1999) and Toy Story 3 (2010) as well as a musical leitmotif throughout the whole Toy Story franchise. The song was nominated for both the Academy Award for Best Original Song and the Golden Globe Award for Best Original Song, but lost both to "Colors of the Wind" from Disney's Pocahontas.

Who sings the song you got a friend in me? Let's have some stream of consciousness first.
The relevant information to answer the above question is: "You've Got a Friend in Me" is a song by Randy Newman. So, the answer is Randy Newman.