The 32-year-old former England right-back joined the Potters from Liverpool in 2015 and has made 50 appearances in all competitions.
Johnson, whose existing contract was due to expire this summer, said the new deal was a "no-brainer".
"I've really enjoyed my time as a Stoke City player so far," he added.
"People made me feel really welcome from the moment I walked through the door two years ago and it's a good place to be.
"I still feel as though I've got plenty to offer as a player and want to continue to help Stoke City move forward," he added.
Manager Mark Hughes said that it would be "foolish" to let a player of Johnson's ability leave.
"He's 32 and remains a key figure in my plans and needless to say, I'm delighted he has signed a contract extension," added the 53-year-old.

The firm, which makes a vast array of consumer products including Ben & Jerry's ice-cream, Lipton tea and Dove soap, said sales fell 2.7% to €48.4bn ($56.1bn; £37.1bn).
Excluding the effect of acquisitions and unfavourable exchange rates, underlying sales rose 2.9%,
Analysts had expected a 3.1% rise.
Despite the weaker-than-expected sales, Unilever reported a 7% rise in pre-tax profit to €7.6bn for the full year.
Unilever chief executive Paul Polman said it had been a "challenging year for our industry", and warned he did not expect a "significant improvement" in market conditions in 2015.
"We expect our full-year performance to be similar to 2014 with the first quarter being softer but growth improving during the year".
Unilever said underlying sales growth in emerging markets, where it makes more than half its sales, slowed to 5.7%.
The firm has been hit hard by a combination of slowing growth in China, a recession in Brazil as well as western sanctions on Russia.
Unilever cut 1,400 jobs last year and Mr Polman said due to the "low growth environment" it would continue to cut costs and simplify the business.
The firm has recently sold a number of its products, including its Slim-Fast brand and Ragu and Bertolli pasta sauces.

He was being questioned about problems with a Trident missile test last June.
The ex-defence minister said that "years ago" a Seaslug aircraft missile was "fired into Wales" by mistake.
It is believed he was referring to an incident in Cardigan Bay in 1958 involving HMS Girdle Ness, when a missile crashed into a hillside.
Giving evidence to the Commons Defence Committee on Tuesday, Lord West said: "Years ago we had an aircraft missile called the Seaslug missile and we fired one into Wales."
"Those sort of things happen but you don't go and talk to the prime minister about that, unless their constituency happens to be there," he added.
Stoke City defender Glen Johnson has signed a one-year contract extension that will keep him at the club until the summer of 2018.
[NEXT_CONCEPT]
Consumer goods giant Unilever has reported lower-than-expected full-year sales after demand for its products in emerging markets continued to slow.
[NEXT_CONCEPT]
A surface-to-air missile was once accidentally fired into Wales by the Royal Navy, the Labour peer Admiral Lord West has told MPs.