Pique, 25, was injured after 17 minutes in the clash with goalkeeper Valdes, which appeared to leave him briefly unconscious.
The centre-back tried to play on but was substituted eight minutes later and taken to hospital with suspected concussion.
A statement from Barcelona said: "Gerard Pique has been discharged from hospital after follow-up medical tests proved satisfactory.
"The Barcelona FC defender spent the night in hospital under observation after a heavy collision with Didier Drogba and Victor Valdes in the early stages of the match against Chelsea. The player will now rest for a week before being re-assessed.''
Barca were held to a 2-2 draw by 10-man Chelsea at the Nou Camp, losing 3-2 on aggregate.