Sydney FC On 22 June 2010, Antonis made his debut for Sydney in a friendly game against
Macarthur Rams at
Campbelltown Stadium. On 5 July 2010, Sydney signed him to a three-year contract. Antonis made his competitive debut for Sydney FC in a 2–1 loss to
Wellington Phoenix on 11 September 2010. Antonis scored his first goal for Sydney FC on 16 February 2013 against
Adelaide United. After rupturing a muscle in his thigh, Antonis was out for 9 months, which thwarted his move overseas. In February 2014, he scored against
Perth Glory in his first game since returning from injury.
Speculation and trials After signing with Sydney FC, he was linked with possible moves to
Everton,
Inter Milan and
Marseille. Much of the speculation was based on his close personal ties with Everton and Socceroo star
Tim Cahill, further sparked by a 25-minute cameo in a friendly match for Sydney FC against Everton at
ANZ Stadium on 10 July 2010. In February 2012, Antonis reiterated his commitment to Sydney FC and the remainder of his three-year contract, stating that he was more than happy being at the club. In April 2012, Antonis travelled to Germany to trial with
Bundesliga club
Borussia Mönchengladbach as a potential replacement for
Roman Neustadter. but was not signed. At the conclusion of the 2012–13 season, Antonis was approached by Dutch club
FC Utrecht for a trial, but signed a four-year deal with
Italian Serie A club
Parma instead after Parma triggered a release clause in his contract with Sydney. However, the deal never went through and Antonis returned to Sydney FC.
PAOK The 21-year-old returned to Sydney from preseason camp on the Gold Coast with News Corp reporting a $500,000 bid for the midfielder from
PAOK FC. Greek sources stated that Antonis spoke at length with former Danish international and Technical Director of PAOK
Frank Arnesen on the prospects of completing the move to his ancestral country and the planning of PAOK's title aspirations that season. Antonis made his debut for PAOK in the
Greek Cup match away to Chania on 3 December 2015, coming on as a 64th-minute substitute for
Eyal Golasa. He made his Greek Super League debut on 21 February 2016 away to Panathinaikos as an 84th-minute replacement for
Giannis Mystakidis.
Loan to Veria After failing to break into the starting team at PAOK, Antonis moved to Greek Super League outfit
Veria FC, coached by
Georgios Georgiadis, a former
PAOK favourite as a player. Antonis signed a one-year loan deal with Veria on 31 August 2016. He made his first appearance on 16 October 2016 as an 88th-minute substitute for Sisinio González Martínez in an away match at Atromitos.
Loan to Western Sydney Wanderers As at PAOK, he struggled to break into a starting position, and was returned to PAOK only to be immediately loaned to
Western Sydney Wanderers FC for the remainder of the
2016–17 A-League season. He made his debut for the Wanderers in an away match against the Brisbane Roar on 28 January 2017 as a 77th minute substitute for Mitch Nichols.
VVV-Venlo After his short-lived loan spell with the Wanderers, PAOK made it clear to Antonis that he wasn't in their plans. On 8 July 2017, it was announced that Antonis had signed with Dutch
Eredivisie side
VVV-Venlo on a two-year deal.
Melbourne Victory Released by
VVV-Venlo on 3 January 2018 without having made a single league appearance for the club, Antonis then signed a 2.5-year contract with
Melbourne Victory of the
A-League where he made 40 appearances before moving on yet again, to
Suwon Samsung Bluewings of the
K-League.
Return to Western Sydney Wanderers On 25 July 2021, Antonis signed a three-year deal with the
Western Sydney Wanderers. His first season he often alternated between starting and coming off the bench. Following the replacement of coach Carl Robinson with Marko Rudan, Antonis was frozen out by club leadership in an effort to force him to agree to leave the club which would free up salary cap room and his squad position. On 24 May 2023, it was announced that his contract with Western Sydney Wanderers had been terminated effective immediately.
Melbourne City Antonis joined
Melbourne City ahead of the
2023–24 A-League season. He became the first player to play professionally for all four Melbourne and Sydney derby teams, beating
Josh Brillante by a matter of days ==International career==