The Mirror says Ball joined the Millers for an undisclosed fee and has penned a three-year deal at the AESSEAL New York Stadium.
The Spurs' Academy product, has also enjoyed time at Cambridge United, spent last season on loan at Glasgow Rangers and they were keen to sign him on loan once again.
Rotherham boss Alan Stubbs told the club's website: “First of all we're delighted that we've managed to get the deal concluded and Dominic is a player I know quite a bit about from my time at Hibs, with him playing at Rangers on loan from Tottenham.
“He did very well and I think any young player going into that environment at Rangers is a big ask, but he fitted into it very well and he was very comfortable with the situation. We're delighted that we've managed to sign him."