The 22-year-old has put pen-to-paper on a three-year contract at the Stadium of Light, with the Black Cats holding the option to extend his deal into a fourth year.
Ballard, who has amassed 15 caps already for the Northern Ireland national team, scoring twice, has spent the last two seasons out on loan in the EFL.
First, he joined Blackpool when the Seasiders were in League One during the 2020-21 season, playing alongside new team-mate Elliot Embleton when he was also on-loan at Bloomfield Road, and the centre-back was a major part of their promotion to the second tier.
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Then, Ballard signed for Millwall of the Championship for the 2021-22 campaign, appearing 31 times in the league for the Lions as they finished in eighth position.
Despite his young age, Ballard brings a decent amount of experience to Alex Neil’s back-line at the Stadium of Light, and he’s sent a message to Sunderland fans following confirmation of his arrival.
— Daniel Ballard (@dg_ballard) June 30, 2022
“Delighted to have joined Sunderland,” Ballard wrote on Twitter.
“Huge club with big ambitions, can’t wait to play my part.”
With Leon Dajaku already signed up on a permanent deal following the club’s promotion from League One, Sunderland fans were excited to see who the first new arrival would be.
And in the form of Ballard, the Black Cats have secured the signature of a player that they could end up selling for mega money if he continues his rate of progression.
Whilst it was always going to be hard to break through at Arsenal, Ballard proved himself to be a very solid central defender for Millwall last season.
Now, with his best years ahead of him, Ballard could really be the player that Alex Neil builds his team around, and he certainly offers a presence at the back.