While there were various theories regarding the composition of the work, Alan Tyson's research identified the commencement period as around late 1783, in Linz. This sonata was published in the summer of 1784 by Torricella as Op. 7, along with the Piano Sonata K. 284 (the so-called "Dürnitz Sonata") and the Violin Sonata K. 454.

In the summer of 1783, Mozart, accompanied by his wife Constanze, made his final return to Salzburg in his lifetime, stopping in Linz on their way back to Vienna. It is believed that he composed the "Linz Symphony" K. 425 at this time and commenced work on this sonata concurrently, with its completion likely occurring after their return to Vienna.

First Movement: B-flat Major, 4/4 time, Sonata Form

The main theme, characterized by appoggiaturas and descending melodic lines, determines the overall character of the movement. The first subordinate theme (m. 23 ff.), which begins with a stepwise descending figure, and the other subordinate theme (m. 39 ff.), characterized by descending arpeggios, may be considered to have been spun off from the main theme.

The latter half (m. 64 ff.) begins in the dominant key of F major with the main theme, but an improvisatory passage quickly unfolds over an Alberti bass. Modulations to the dominant key recur through F minor, C minor, and G minor, leading to the dominant chord of the tonic B-flat major. With the insertion of G-flat, the note of the parallel minor, like a signal, the main theme is recapitulated (m. 94 ff.). The two subordinate themes are also recapitulated in the tonic key (m. 119 ff. / m. 135 ff.), and the movement concludes with a coda similar to the first half (exposition) (m. 59 ff. / m. 161 ff.).

Second Movement: E-flat Major, 3/4 time

It is composed in a two-part form, similar to sonata form, with the dominant theme recapitulated in the tonic key, but the latter half features improvisatory ornamentation. It is noteworthy that a stepwise descending figure, reminiscent of the main theme of the first movement, is inserted within the opening theme (m. 3, beat 3).

The dominant theme (m. 14 ff.) is also characterized by stepwise descent and ornamentation with turn figures. The motive of repeated notes with portamento plays an important role in the latter half.

In the latter half (m. 32 ff.), the motive of repeated notes from the dominant theme reappears repeatedly, passing through F minor, C minor, A-flat major, and D-flat major, leading to the dominant seventh chord of E-flat major.

After the opening theme is recapitulated with improvisatory ornamentation (m. 51 ff.), the dominant theme is recapitulated in the tonic key (m. 64 ff.).

Third Movement: B-flat Major, 2/2 time, Rondo Form

The rondo theme of the final movement is also characterized by descending figures and appoggiaturas.

The theme appearing in the parallel minor, G minor (m. 65 ff.), also employs the stepwise descending figure of 16th-note triplets from the rondo theme, indicating an intended thematic relationship.

The rondo theme, returning from m. 112, develops, and improvisatory passages unfold. At its culmination, it stops on the second inversion of the tonic chord from the double dominant, and a cadenza is provided (m. 171).

The rondo theme then returns again, but this time an Eingang (m. 198) is inserted, leading to the coda.