The Newcastle defender - who captained the Magpies against Chelsea on Sunday - has two caps for his country but withdrew from international duty in May 2017 in order to focus on his club career.
At the time, he had played through the pain barrier on several occasions to help United return to the Premier League, but he had always made it clear that he had not closed the door on his international career and hoped to represent the Dragons again in the future.
Former Manchester United legend Giggs replaced Chris Coleman in January and has named Dummett in his 25-man squad ahead of Wales' inaugural UEFA Nations League matches in September.
"I spoke to him when I took over," explained Giggs at a press conference on Wednesday. "He was coming back from an injury and Newcastle were fighting relegation so he didn't think it was the right time so I left it open and we spoke again after the Chelsea game.
"He was really excited and felt it was difficult for him coming away and not playing at the time, which you can understand, especially when you're at a big club.
"But he's playing regular Premier League football and was available. He's always been positive in our conversations and I look forward to having a player of his quality."
Giggs' men will face the Republic of Ireland at home on September 6th before travelling to Aarhus to face Denmark on September 9th.
The full Wales squad is: Wayne Hennessey (Crystal Palace), Danny Ward (Leicester City), Adam Davies (Barnsley), Chris Gunter (Reading), Connor Roberts (Swansea City), James Chester (Aston Villa), Ashley Williams (Everton, on loan at Stoke City), Chris Mepham (Brentford), Tom Lockyer (Bristol Rovers), Ben Davies (Tottenham Hotspur), Paul Dummett (Newcastle United), Declan John (Swansea City), Ethan Ampadu (Chelsea), Joe Allen (Stoke City), Matthew Smith (Manchester City, on loan at FC Twente), Aaron Ramsey (Arsenal), Andy King (Leicester City), Joe Ledley (Derby County), Harry Wilson, (Liverpool, on loan at Derby County), David Brooks (AFC Bournemouth), Tom Lawrence (Derby County), Ben Woodburn, Liverpool, on loan at Sheffield United), Gareth Bale (Real Madrid), Sam Vokes (Burnley), Tyler Roberts (Leeds United).
