Both the club and the Brazilian forward himself have confirmed he will formally put pen to paper on Monday and join the Camp Nou giants this summer
The forward himself also broke the news through his Instagram and Facebook accounts and revealed his appearance against Flamengo on Sunday would be the last he makes for his boyhood club.
A Barcelona statement read: "FC Barcelona and Santos have agreed to terms for Neymar da Silva Santos Junior. The Brazilian forward will don the Blaugrana strip for the next five seasons. "
Shortly afterwards, the club publicly welcomed him on Twitter and posted a player profile on their official website.
The transfer deal for Neymar, who opted to join Barca over Real Madrid, will be worth around €28 million with the player's deal tying him to the Camp Nou club until the summer of 2018.
The Brazil international will earn around €7m-a-year at Barcelona, who have also agreed to play two friendly matches against Santos - one at home and another away - as part of the deal.
Neymar said: "It is not going to hold out until Monday. My family and friends already know my decision. On Monday, I will sign a contract with Barcelona.
"I want to thank the fans of Santos for these incredible nine years. My feeling for the club and the fans will never change. It is eternal!
"Only a club like Santos FC could give me everything I experienced on and off the field. I thank the wonderful Peixe fans who supported me even in the most difficult moments.
“I insisted on playing my last match, tomorrow, in Brasília. I want to have the chance to walk into the pitch once more, wearing this shirt and hearing the fans sing my name.
"Titles, goals, dribbling, celebrations and songs that fans created for me will be forever in my heart.
“This is a different moment for me. I'm sad (because of the goodbye) and happy (to have a new challenge). May God bless my choices…”
Neymar's contract with Santos had been due to run until next summer's World Cup but he was always widely expected to move to La Liga this year so the club could secure a transfer fee for his services.
The 21-year-old has been named in the Brazil squad for the Confederations Cup tournament in June, after which he will link up with his new Barca team-mates ahead of next season.