The 23-year-old striker was sentenced to 18 months in jail on October 4.
A statement on the club's official website read: "Following consultation with the legal team of Gary Madine, Sheffield Wednesday have been made aware of their intention to lodge an appeal following the 23-year-old's recent trial at Leeds Crown Court.
"Until the conclusion of this or any other legal process, the club will make no further comment."
Madine, who has a previous conviction for knocking a man out in a Carlisle pub, punched Wednesday fan Daniel Beresford in the Paris Bar in Sheffield city centre in February last year, breaking his nose.
Four weeks later, he punched bricklayer and Sheffield United fan Reece Hall in the city's Viper Room club, shattering his cheekbone.
He was jailed after being found guilty by a jury following a week-long trial last month.