It was originally projected by engineer and urban planner Ildefons Cerdà as one of the city's wide avenues, which along with Avinguda Meridiana would cut the rationalist grid he designed for l'Eixample (Catalan for extension).

However, Plaça Catalunya, equally a new addition to the city of Barcelona, and connecting Ciutat Vella and Eixample, and therefore occupying a more privileged position in the urban area, would finally become the centre.

The different regimes that held power in Catalonia and Spain during the 20th century sought to change the city's street names, and Avinguda Diagonal was permitted no exception.

After the completion of its central section, from the current Plaça de Francesc Macià towards Glòries, it soon became one of Barcelona's most popular avenues and an ideal place for the Catalan aristocrats and bourgeoisie to exhibit their carriages.

A popular consultation (the word referendum being banned by Spanish law) was scheduled for May 2010 between two reform proposals, the so-called rambla or boulevard.