Being named co-captain is another achievement for Dragons skipper and Clubman of the Year Hill, who started every game during the NatWest Six Nations and was named in the team of the tournament.
Hill has won 15 caps, was Jamie Roberts' vice-captain last summer and was also called into Gatland's Lions squad last summer to provide injury cover. He will be co-captain with Cardiff Blue Ellis Jenkins next month.
"It’s a great honour for them and we’re looking to see how they develop from a leadership perspective," said Gatland upon announcing Jenkins and Hill as co-captains.
"Cory to me is the most improved player in Welsh rugby in the last 18 months and since he’s come into the squad he has developed and taken on a real core role in terms of line-out calling and leadership in that role as well as captaining the Dragons. We see that as part of his development and his leadership.
"We knew when he came into the squad that physically there had to be an improvement; he's a good ball carrier but we had to put some weight on him.
"He's done that, ideally you'd like another 2 or 3kgs on him to be able to compete at that level but he has definitely been one of the most improved players in the squad.
"There wasn't a massive amount of expectation from us but it's been pleasing to see a player like that develop.
"He has come on and deserves this opportunity because he has been an important part of the squad over the last year or so."
However, Gatland has warned the Dragons skipper that competition is fierce in the second row as Wales prepare for next year's World Cup.
"With Alun Wyn Jones and Jake Ball to come back, Luke Charteris now back in the fold, Bradley Davies, Seb Davies, Adam Beard, it's a pretty competitive position," said the head coach.
"Cory knows that he is going to have to continue to improve. He gets a great chance to keep working and developing because he is outstanding in the role of lineout caller, is a fantastic professional and deserves the accolade that has been given to him and the chance to see how he handles the next challenge."
Usual captain Alun Wyn Jones is rested for the summer tour along with fellow Lion Taulupe Faletau, who led the side against Italy in the Six Nations.
Past skippers Sam Warburton and Dan Lydiate are injured whilst Jamie Roberts is not selected for this tour.
"Co-captains is something that I've never done before and we thought it was a good opportunity, particularly so that they can support each other rather than all the responsibility being on one person," said Gatland.
"It's a big role to take given the relative inexperience of the squad, so the two of them supporting each other and getting the support from other key players that have been around for a while will be good.
"Part of the thinking with this squad and taking 31 for the three matches, is that everyone of the 31 will be involved in the games and that’s important as we don’t want half a dozen players not involved, so that’s the reason for the co-captains. There might be a situation where one is on the bench or not involved.
Wales squad
Forwards: Rob Evans (Scarlets) (25 Caps), Wyn Jones (Scarlets) (8 Caps), Nicky Smith (Ospreys) (18 Caps), Elliot Dee (Dragons) (7 Caps), Ryan Elias (Scarlets) (2 Caps), Tomas Francis (Exeter Chiefs) (31 Caps), Samson Lee (Scarlets) (38 Caps), Dillon Lewis (Cardiff Blues) (2 Caps), Adam Beard (Ospreys) (2 Caps), Bradley Davies (Ospreys) (62 Caps), Seb Davies (Cardiff Blues) (4 Caps), Luke Charteris (Bath) (74 Caps), Cory Hill (Dragons) (15 Caps) (Co-Captain), James Davies (Scarlets) (1 Cap), Ellis Jenkins (Cardiff Blues) (6 Caps) (Co-Captain), Ross Moriarty (Gloucester) (20 Caps), Josh Navidi (Cardiff Blues) (11 Caps), Aaron Shingler (Scarlets) (17 Caps).
Backs: Aled Davies (Scarlets) (8 Caps), Gareth Davies (Scarlets) (32 Caps), Tomos Williams (Cardiff Blues) (*uncapped), Gareth Anscombe (Cardiff Blues) (15 Caps), Rhys Patchell (Scarlets) (8 Caps), Hadleigh Parkes (Scarlets) (6 Caps), Owen Watkin (Ospreys) (4 Caps), Scott Williams (Scarlets) (55 Caps), Josh Adams (Worcester Warriors) (2 Caps), Hallam Amos (Dragons) (15 Caps), Steff Evans (Scarlets) (9 Caps), George North (Ospreys) (73 Caps), Tom Prydie (Scarlets) (5 Caps).
2018 summer tour schedule
Saturday, 2 June
South Africa v Wales (Robert F. Kennedy Memorial Stadium, Washington, USA)
Saturday, 9 June
Argentina v Wales (San Juan del Bicentenario Stadium, San Juan)
Saturday, 16 June
Argentina v Wales (Estadio Brigadier López, Santa Fe)
Dragons Season Membership is now on sale for 2018/19 with an early bird offer available until 21st May, saving adults up to £30. CLICK HERE for more information about membership.
