Gardener and Larsson's moves to the Stadium of Light were confirmed last week as the exodus at St Andrews continues following the Blues' relegation from the Premier League, and Phillips believes the pair can star in their new surroundings.
"They're great signings," he said. "They've both got so much to offer already, and one of the best things about them is that they're still young lads and only going to get better in the seasons ahead.
"I enjoyed working with them at Birmingham City, and I think that Sunderland fans will really enjoy what they bring to a team. They're the sort of players that Sunderland fans love," he added "They're strong characters who give their all in games and don't give up.
The duo join new signings Ji-Sung won, Keiren Westwood and Connor Wickham at the club,
as Steve Bruce attempts to build a squad capable of contesting for a European spot.