The Yorkshire batsman has been recalled for the opening Test against Pakistan at Lord’s starting next Thursday.
It will be his first Test for almost a year after he was dropped after the second Ashes Test at Lord’s last July.
The 26-year-old left-hander, who was a non-playing member of the Test squad that toured South Africa last winter, will bat at No 5, with county colleagues Joe Root and Jonny Bairstow slotting in at No 3 and No 6 respectively.
Ballance was preferred to Ben Stokes, Jos Buttler and Scott Borthwick, with England resisting the temptation to play Stokes as a specialist batsman while he recovers from knee surgery.
“I was just doing a bit of grocery shopping when I got the call from (national selector) James Whitaker,” said Ballance, who replaces Nick Compton from the recent series against Sri Lanka.
“It’s all come as a bit of a surprise, and obviously it’s a great feeling to be back in the squad, especially when you’ve been out of the side for a while.
“It was about this time last year when I got left out, and it does feel like a long time ago.
“I still got in the squad for South Africa, so I’ve still been part of it, but I haven’t played and, obviously, that’s what you want to be doing.
“But that’s how it goes; it’s part and parcel of playing cricket.
“I’ve had some time away, the chance to work on my game, and I feel like I’ve got back to where I want to be.”
Ballance earned his recall on the back of his first County Championship hundred of the season against Middlesex last week.
He scored 132 in the match at Scarborough to follow an innings of 78 in the previous Championship game against Durham at Chester-le-Street.
“I’ve felt good the last few weeks,” he added. “I’d been playing well, but just not got that big score that gets you noticed.
“So I was happy with the way I played there (at Scarborough), especially getting a century, and spending a long time in the middle.
“Middlesex have got a good attack, with Murtagh, Finn and Roland-Jones.”
Toby Roland-Jones, who played a key role in Middlesex’s innings victory at North Marine Road, is a new face in England’s 12-man squad.
He will vie for a place with fellow pace bowler Jake Ball, who was in the squads to face Sri Lanka, with James Anderson absent with a shoulder injury.
Ballance, who averages 47 from 15 Tests, is greatly admired by chief selector Whitaker, who said: “He has been in recent form with the bat for Yorkshire in the Championship.
“Gary is mentally strong and we feel that he will add quality and experience to England’s middle-order.”
England (from): Cook (captain), Ali, Bairstow, Ballance, Ball, Broad, Finn, Hales, Root, Roland-Jones, Vince, Woakes.