The Albion defender pleaded guilty to driving while disqualified and driving without insurance when he appeared at Brighton Magistrates' Court on Friday.
The 26-year-old right-back, who gave his address as Sutton Coldfield, West Midlands, was banned from driving for 17 months in July last year.
Sussex Police said they stopped the Chilean international player's Audi Q7 sports car in Brighton city centre, East Sussex, just before 11am on December 17.
Brighton magistrates disqualified Jara from driving for 12 months and ordered that he also pay £100 in costs.
The player, who moved to West Brom for £1.4million in 2009, joined Championship Brighton on loan in October but was recalled by the Premier League side last month and has started their last two matches.
