Hartley is one of three hookers in Warren Gatland's 37-man squad which heads to Australia at the end of May.
The tourists have a 10-match schedule which includes a tour curtain raiser against the Barbarians in Hong Kong, fixtures against all five Australian Super Rugby teams and the three tests against the Wallabies themselves, which will be played in Brisbane (June 22nd), Melbourne (June 29th) and Sydney (July 6th).
"I can't stop smiling," Hartley said. "I was very aware that the squad was being announced at 11 o'clock, which was the same time that training was starting, and Jim Mallinder came up and whispered it into my ear that I'd been selected.
"I'm very humbled. It's the pinnacle of rugby, and it hasn't really sunk in yet. I'm just happy that the sleepless nights are over now! I'd put a lot of pressure on myself to try and make it, but it's out of your hands and it's the coaches who are the ones who pick the squad.
"For it to actually happen is quite surreal."
Hartley's selection means that the Saints have had players in six successive British and Irish Lions touring parties, the Saints skipper following in the footsteps of Euan Murray (South Africa, 2009), Steve Thompson (New Zealand, 2005), Matt Dawson and Ben Cohen (both Australia, 2001), Dawson, Tim Rodber, Gregor Townsend, Nick Beal and Paul Grayson (all South Africa, 1997), and Ian Hunter and Martin Bayfield (both New Zealand, 1993).
Other notable Saints who have worn the red shirt of the British and Irish Lions with distinction include scrum-half Dickie Jeeps (three tours), centre Jeff Butterfield (two tours) and wing Keith Savage (two tours). In all the club has had representatives on 11 Lions tours.