Hanley signed a five-year deal with the Magpies on Thursday.
Newcastle United manager Rafael Benitez has admitted his delight at signing Blackburn Rovers signing Grant Hanley and explained to the club's official website why he was so desperate to bring in the defender.
Hanley signed a five-year deal with the Magpies on Thursday after a third offer reportedly worth around £5.5 million was accepted by Rovers.
The 24-year-old Scottish international becomes Benitez's sixth signing of the summer and adds to fellow defensive recruits Isaac Hayden and Jesus Gamez.
Newcastle had been chasing Hanley for some time and though the Lancashire club and their manager Owen Coyle held on resolutely, the Magpies eventually got their man.
Benitez admitted his pleasure at finally sealing the deal and explained why he was so determined to bring the centre-back to St. James' Park, citing Hanley's experience and strength as key factors.
The Spanish boss told nufc.co.uk: "I am very pleased to bring Grant Hanley to our project to add his hard work and potential to our squad.
"It was clear that we needed another central defender and we were seeking someone with good experience in the Championship.
"Grant is a young player with a lot of ambition to improve and keep growing with us. He is also a strong defender, fast and with personality, a player that surely will increase competitiveness in his position."
Though he is only 24, Hanley certainly has a great deal of Championship experience to bring to his new club, having been a regular for Rovers in the second tier in each of the last four seasons.
He will now compete with the likes of Chancel Mbemba and Jamaal Lascelles to become a regular under Benitez this season.