Camavinga picked up an ankle problem while representing France against Chile on Tuesday evening, and the midfielder was unable to train alongside his teammates on Thursday.
Meanwhile, neither Valverde nor Bellingham were involved in the main session on Thursday, with the pair instead working in the gymnasium after representing Uruguay and England respectively during the international break.
However, according to Mundo Deportivo, all three were able to train on Friday, handing Real Madrid a huge boost ahead of their clash with Athletic.
There had been fears that Camavinga could be facing weeks on the sidelines; the injury is said to have been an impact one rather than a sprain, though, and he is in line to take to the field at Bernabeu.
Camavinga has featured on 32 occasions for Real Madrid this season, providing two assists, and he played 72 minutes of his side's 4-2 win over Osasuna before the international break.
Valverde, meanwhile, has made 41 appearances at club level this term, scoring once and providing eight assists.
Bellingham has only featured in one of Real Madrid's last five league games, as he was absent against Rayo Vallecano and Sevilla through injury, before sitting out the matches with Celta Vigo and Osasuna before the international break due to a suspension.
The 20-year-old has scored 20 goals and registered nine assists in 31 appearances at club level this season, and he will enter the clash with Athletic off the back of scoring for England in his country's 2-2 draw with Belgium on Tuesday night.
How is the rest of the Real Madrid Read on sportsmole.co.uk