There was also a first Test call up for Somerset spinner Dom Bess after his county teammate Jack Leach was ruled out of the two-match series due to a thumb injury.
England will play two tests against Pakistan, with the second starting on June 1 at Headingley.
But, after England's tour series losses in Australia and New Zealand, top-order batsman James Vince was dropped after a run of low scores at Test level despite the Hampshire batsman making an unbeaten 201 against Somerset on Monday.
Buttler, who played the last of his previous 18 Tests in December 2016 but is an inked-in white-ball player for his country, will be back as a specialist batsman - with Jonny Bairstow retaining the wicket-keeping gloves.
Bess, 20, has an average of 22.49 from 16 first-class games.
Buttler will bat at seven for England at Lord's next week with Smith deciding his counter-attacking flair is just what the team needs after a winter of batting failures. The selection panel feels that this is the flawless moment to reintroduce Jos to Test cricket, where he has already enjoyed some success, including a stint playing as a specialist batsman at number seven.
'Dom Bess has made an excellent start to his first-class career, ' said Smith, who pipped Andy Flower to become England's new national selector. Aesthetically pleasing at the crease, Vince struggled to back up his obvious quality with significant numbers - he has now played 22 Test match innings and averages a disappointing 24.90 after enduring a hard time of it during the Ashes series against Australia in the winter.
"Dom's strong form, character and all-round abilities presented a compelling case for selection", Smith said.
Alastair Cook, Mark Stoneman, Dawid Malan, Joe Root (capt), Jonny Bairstow (wk), Ben Stokes, Jos Buttler, Chris Woakes, Mark Wood, Stuart Broad, James Anderson, Dominic Bess.