The Croydon Advertiser reports Inniss has been jailed for 14 weeks after pleading guilty to assault by beating.
Inniss, 21, was given the prison sentence at Bexley Magistrates' Court, in relation to an incident on May 27 at Time Bar.
He was sentenced on Wednesday and began his prison sentence on the same day.
Inniss will be appealing his sentence on Monday at Croydon Crown Court, the Crown Prosecution Service confirmed to the Advertiser.
He pleaded to guilty to the offence on August 26 at Bromley Magistrates' Court - days before he moved to League Two side Southend United on a season-long loan deal on transfer deadline day.