The Argentina global takes over from Iniesta following his move to Vissel Kobe in the J League at the end of the 2017-18 campaign.
Barcelona have decided upon their captains for the season ahead after Andres Iniesta left at the start of the summer, and Javier Mascherano departed in January.
Roberto, meanwhile, did not become a senior squad member full time until 2013 but made his debut in 2010 in the Copa del Rey and his first Champions League appearance against Real Madrid in the 2011-12 semifinals, thereby representing the club earlier than Jordi Alba.
Messi was named Barcelona's second captain in 2015 and, having also skippered Argentina, was the obvious choice to take over from Iniesta.
Legitimising Barca's claim to nurturing talent over heavy expenditure, all four players are graduates of the famed La Masia.
Argentine captain, Lionel Messi will captain Barcelona this season with Sergio Busquets and Gerard Pique acting as his lieutenants.
Barca lost just one match on their way to winning La Liga last term, and kick off the new season against Alaves on August 18.