Alex Williams, 22, from Christchurch, had failed to appear in court for sentencing in November, but was arrested in the town on Sunday.
He appeared at Bournemouth Crown Court earlier and was sentenced to 20 months in prison for violent disorder.
Williams was also sentenced to a further two months for failing to appear in court.
Detectives had appealed to the public to help locate him after he failed to show up.
The gang's offences included throwing a liquid, thought to be ammonia, at two victims who were each left blind in one eye.
Four men were jailed for the attacks.
In November Joe Warne, 21, was sentenced to 20 years; Reece Watkins, 22, was sentenced to 18 years; Dominic Barker, 20, was given 16 years and Piers Fox-Havilland was jailed for 12 years.
The men, who lived in the London area, were also sentenced to 12 years for conspiracy to rob and eight for possession of imitation firearms - to run concurrently.
Dorset Police said the gang was charged following a lengthy investigation into attacks at locations including Boscombe and Christchurch.
A man who was part of a five-strong gang that committed violent acts in Dorset has been jailed.