The Glasgow lock is one of five uncapped players in the 28-man squad named by head coach Andy Robinson.
The others are fellow Warriors forwards Ryan Grant and Rob Harley plus Edinburgh backs Tom Brown and Dutch-born Tim Visser.
Ryder said: "Without doubt this is the proudest moment of my professional rugby career. When I signed my contract with Glasgow I hoped to make an impact with a Warriors team that was on the up.
"Now to be going Down Under with Scotland is massive. I know that it is going to be a hugely physical and combative tour but that only adds to the attraction for me."
Ross Ford carries on as skipper for Test matches against Australia, Fiji and Samoa despite the side's Six Nations whitewash. Visser will miss the first game as he only qualifies for selection from June 12.
Head coach Robinson said: "This is a tough tour for Scotland. We'll be playing against three attack-minded teams on their own turf. But it's an important opportunity to start the rebuilding process after a disappointing Six Nations.
"One quarter of the squad has yet to start an international but we've seen from the manner in which Edinburgh and Glasgow have finished the domestic season that there's confidence that we will be looking to build on."
Squad – Backs: Joe Ansbro (London Irish), Mike Blair, Tom Brown (both Edinburgh), Chris Cusiter (Glasgow Warriors), Nick De Luca (Edinburgh), Max Evans (Castres), Alex Grove (Worcester Warriors), Stuart Hogg (Glasgow), Greig Laidlaw (Edinburgh), Sean Lamont (Scarlets), Matt Scott (Edinburgh), Tim Visser (Edinburgh), Duncan Weir (Glasgow).
Forwards: John Barclay (Glasgow), Geoff Cross, Ross Ford (both Edinburgh), Ryan Grant, Richie Gray, Dougie Hall, Robert Harley, Alastair Kellock (all Glasgow), Scott Lawson (Gloucester), Euan Murray (Newcastle Falcons), Ross Rennie (Edinburgh), Tom Ryder (Glasgow), Alasdair Strokosch (Gloucester), Richie Vernon (Sale Sharks) and Jon Welsh (Glasgow).