The Brazil global has committed to a new deal that will expire on June 30, 2022.
The 29-year-old joined in 2007, making nearly 300 appearances as Real have maintained their status as one of the most successful clubs in world football.
The full-back has more than lived up to the billing in the ten years since and claimed his fourth La Liga title and third Champions League crown in May.
The Spanish giants announced that Marcelo will appear in a press-conference at the Bernabeu on Thursday afternoon to formally announce the deal.
The news came on the same day that the Brazilian received a two-game ban for kicking out at an opponent during Saturday's surprise 1-1 draw against Levante.
The suspension means the defender will miss Real's Liga games against high-flying Real Sociedad on Sunday and Real Betis on September 20.
Madrid is seventh in the league standings after three matches, four points behind leaders Barcelona and Real Sociedad.