The club confirmed they have reached an agreement with Benfica yesterday and now he has undergone his medical.
Full details of the transfer were not released, but Semedo is expected to put pen to paper on a 5-year contract for a fee of €30 million plus a series of add-ons that potentially takes the final value of the deal close to €50m.
The departure of the Portugal right-back from Lisbon continues a trend akin to a mass exodus of top talent from the Primeira Liga.
He has six international caps but was sent off in this month's Confederations Cup third-place playoff match.
He should be announced as a Barcelona player today.
"He was a key player in Benfica's treble-winning campaign and in two seasons has played 63 games, scoring two goals in the Portuguese League and one more in the Champions League".
Nelson Semedo is 23 years old. As well as the aforementioned André Silva, namesake Bernardo Silva moved to Manchester City in the EPL after his magnificent showings for Monaco.
The Catalan side hope to have Semedo travel with the squad next Wednesday for their pre-season tour of the United States.