Court officials said he had been found guilty of repeated bodily harm, attempted bribery, violence against public employees and insult after his arrest in Mykonos.
The 27-year-old England international was one of three people arrested on Thursday after an altercation with police.
“Following the hearing today, I have instructed my legal team with immediate effect to inform the courts we will be appealing,” Maguire said in a statement.
“I remain strong and confident regarding our innocence in this matter - if anything myself, family and friends are the victims.”
Following the hearing, England coach Gareth Southgate withdrew Maguire from his squad for next month’s Nations League matches against Iceland and Denmark.
"As I said earlier today, I reserved the right to review the situation," Southgate, who had initially selected the centre back in his 24-man squad, said in a statement here.