The 48-year-old has signed a four-year contract at the Stadio Olimpico with the option of a fifth season and will start in his new role immediately.
Monchi, whose full name is Ramon Rodriguez Verdejo, had been at Sevilla for more than 30 years after he progressed through Los Blanquirrojos' youth system before making his debut for Sevilla B during the 1988-1989 season.
He made his first-team debut for the club in 1991 but was mainly regarded as a back-up until his retirement in 2000 at the age of 30.
Monchi immediately moved into a sporting director role following retirement with the aim of improving Sevilla's youth academy and setting up an extensive scouting network for recruiting players, something that has received high praise.
He told asroma.com: "I would like to thank Roma president Jim Pallotta and the club's executive team for giving me this opportunity.
Read the full article on eurosport.co.uk: Monchi leaves Sevilla to become Roma's sporting director