The 31-year-old has spent the past three years at Kingsholm, helping the Cherry and Whites lift the European Rugby Challenge Cup in 2015, and still features on a regular basis for the side.
However, Hook has decided to return to Wales at the end of this season and re-sign with Ospreys, the region he left in 2011 to join French Top 14 outfit Perpignan.
The fly-half, who has 81 caps for Wales, began his career in Neath before spending five years with the Pro 12 club, helping them to win the Celtic League title in 2010.
Hook says he has enjoyed the experience of playing abroad but feels it is important for his career and family life that he returns home with Ospreys.
Hook said: "I'm delighted to be going back home next summer.
"It's been fantastic to go away to new places, get some unbelievable experiences in England and France with two great clubs, but I'm coming home to a team that's going places, with good coaches who I know well and a quality squad with some world class players and really exciting young talent.
"It's good for me personally, as a rugby player, and it's the right thing for my family, to be coming home.
"I'm only 31, I'm playing week in, week out with Gloucester and I think I've got plenty to give on the field for a few years to come."
Ospreys should certainly by well covered at the fly half position as Wales internationals Dan Biggar and Sam Davies are also both currently at the club.