Demonstrators included politicians of the center-right People's Party, with Catalan leader Alicia Sanchez Camacho and constitutional parties like Ciutadans, as well as many families.
The parade unfolded in a festive atmosphere with many Spanish and Catalan flags, and a few European Union flags.
The symbol of the movement is a heart broken in two, with a Spanish flag in one half and a Catalan flag in the other. It is the first time that Barcellona has had an anti-independence demonstration on the Spanish national holiday.
Regional police deployed 800 officers to keep public order.
(ANSAmed).