The Belgium international is on the verge of joining the Serie A side ahead of the 2016/17 season, subject to a medical.
And Barca on Sunday afternoon announced their decision to grant Vermaelen permission to fly to Rome on their official Twitter account.
— FC Barcelona (@FCBarcelona) 7 August 2016
Vermaelen has struggled for playing time at the Camp Nou after making the switch from Arsenal in 2014, and made just 16 starts during his time in Spain.