Nadal will be looking to win his 13th title on the clay courts in Barcelona after first lifting the trophy in 2005.
Tournament director David Ferrer said: “Having Rafa in Barcelona is very exciting for the tournament and the expectation will be high to know how far he can go.”
Nadal has enjoyed a sensational start to the year after winning the Australian Open in January coming from two sets down to beat Daniil Medvedev.
That was the 35-year-old’s 21st grand slam title and moved him ahead of Roger Federer and Novak Djokovic in the all-time list of male major champions.
Nadal also won the Mexican Open final last weekend having beaten newly-anointed world number one Medvedev in the semi-finals.
Rafael Nadal will be bidding for a 14th French Open title
The Barcelona Open begins on April 16, just over a month before the start of the French Open in May.
Nadal will be looking to win a record-extending 14th title at Roland Garros after losing to Djokovic in last year’s semi-finals.