The first work to be added to his collection was Alexey Bogolyubov's Ipatievsky Monastery near Kostroma.

[4] He later began collecting primarily works from Western European artists, especially French romantics and realists.

[4] On Sergei's death in 1892, both brothers' collections were donated to the Moscow city administrators.

[6][5] The city converted the brothers' private showroom into a gallery accessible to the public,[5] free of charge.

[4] The official opening of the Moscow City Gallery of Pavel and Sergei Tretyakov, as it was then named, took place on 15 August 1893, with over 700 visitors on the first day.