Republic of Ireland midfielder McCarthy has penned a four-year deal with his boyhood club after allowing his contract at Crystal Palace to expire in the summer and is joined by Tottenham Hotspur’s Hart.
Postecoglou was last week bullish about making two further additions to his squad in a matter of days and it would appear moves for McCarthy and Hart lay behind his confidence.
The switch to his boyhood favourites brings a return to Scotland for McCarthy, who began his career with Hamilton Accies before he made the switch to Wigan in 2009. Four years there gave way to him reuniting with Roberto Martinez at Everton in 2013 – the two following one another that same summer – before he spent the past two seasons at Selhurst Park.
Hart, meanwhile, has signed a three-year deal with the club. The 75-times capped England stopper spent more than a decade at Manchester City, winning the Premier League, FA Cup and League Cup, before loan moves with Torino and West Ham. He joined Burnley in 2018 before spending a season at the London Stadium as Hugo Lloris’ understudy.
The goalkeeping position has been one of great angst for Celtic of late, with last summer’s £5million signing Vasilis Barkas failing to impress, while Scott Bain and Conor Hazard have been unable to hold down the gloves either.
Postecoglou said: “I’m delighted that we have signed two top-class players in Joe and James. Both of them have a wealth of experience at both club and international level, and that is something which can only benefit the squad, and I’m looking forward to working with both of them.
“I know our supporters will be well aware of both players, and I’m sure they’ll welcome them to the club and look forward to seeing both of them play for Celtic in the seasons ahead.”
Hart said: “This is a great moment for me in my career and I am absolutely delighted to be joining a club of Celtic’s stature.
“I know just how big this club is and of the incredible support that it enjoys
“I’m looking forward to meeting up with my new team-mates now and getting to work with the squad and, in particular, the other goalkeepers here.”
McCarthy said: “To have signed for Celtic is a brilliant feeling and this is a special day for me and my family.
“I know all about the club, the size of it and all the success it’s enjoyed, particularly in recent years. I’m looking forward to pulling on the Hoops, playing at Paradise and helping the team deliver more success to these amazing fans in the seasons ahead.”
Both players could make their debuts for Celtic in Thursday night’s Europa League third qualifying round first leg tie against Jablonec, as Postecoglou is able to register two “wildcard” additions to his already-submitted eligibility list to UEFA. Celtic tweeted confirmation that Hart is joining up with the squad in Czech Republic.
Hart and McCarthy bring Postecoglou’s signings total up to six, with Carl Starfelt joining from Rubin Kazan, Liel Abada from Maccabi Petah Tikva, Osaze Urhoghide from Sheffield Wednesday and Kyogo Furuhashi from Vissel Kobe.