"Friends in My Heart" is approximately one minute and thirty seconds long in Kingdom Hearts and the HD remake of Kingdom Hearts Final Mix. In Kingdom Hearts II, the piece is approximately one minute and one second long. For the HD remake of Kingdom Hearts II Final Mix, the piece is extended to one minute and forty-six seconds. Regardless of the game, the piece has a time signature of 4/4, and a tempo of 64 beats per measure.
In Kingdom Hearts and Kingdom Hearts II, the instrumentation includes: strings, piano, synthesizer, and choir-ahs. Although more gentle and softer in tone, this same instrumentation is used in Kingdom Hearts HD 1.5 ReMIX and Kingdom Hearts HD 2.5 ReMIX.
The allure of the piece is in its light-hearted and reminiscent tone created by a lack of complex rhythms and minimal instrumentation. "Friends in My Heart" opens with a four measure introduction, comprised of piano, synthesizer, and choir-ahs. In measure five, the pizzicato technique in the strings section is introduced, adding a slight rhythmic diversity in comparison to the simpler, smoother keyboard and choral parts. In the same measure, the piano part is a leitmotif of Dearly Beloved. Although a slight variation in rhythm, the progression of notes and rhythmic outline is a variation of the Dearly Beloved theme.
