Wong applied for leave to appeal against his sentence after receiving 10 months behind bars in May last year for taking part in an unauthorised assembly.
His lawyers had argued that the sentence was too heavy, and on Wednesday, appeal justices Maggie Poon and Anthea Pang revised the starting point for sentencing from 15 to 12 months, bringing Wong’s term down to eight months after factoring in his guilty plea.
The court upheld the four-month jail sentence meted out to another defendant in the case, Jannelle Leung.
Wong, who was also jailed over other cases, is expected to finish serving his sentences in March.