Chelsea have agreed terms with Fluminense to sign Wallace in the January transfer window, with the fullback to move in the off-season.
The 18-year-old defender is a former Brazil Under-17 international and moves to Stamford Bridge for an undisclosed fee, joining fellow Brazilian youngsters Lucas Piazon and Oscar.
An attack-minded right-back with pace, Wallace has played only 18 league games for the Brazilian side, having made his senior debut earlier in 2012.
However, he has already won three trophies with his club and starred for his country in the South American Under-17s Championship in 2011.
Joining Fluminense in 2005, Wallace has already drawn comparisons to another full-back produced by the club, Real Madrid's Marcelo.