The mercurial scrum-half will return to the England side for the first time since last August on Saturday after being named in Lancaster's team to face South Africa in the third Test.
The 25-year-old missed the World Cup last autumn through injury and was then dropped for the Six Nations over a series of alcohol-related off-field incidents.
Lancaster warned Care he would have to reform his ways to be considered for a recall and the England boss is satisfied the Harlequins half-back has now done that.
Care, who has 32 caps, finished the domestic season well and was one of the standout performers in last week's tour match against the Southern Barbarians in Kimberley.
Lancaster said: "Danny and I go back a long way, back to the academy.
"It is nice to finally coach him again in the starting team and I am looking forward to seeing him perform.
"He had a broad grin on his face when I told him. He is a competitive player and he knows he is in a competitive position with Ben Youngs and Lee Dickson both playing well in the Six Nations.
"I know he was desperately disappointed not to make the first Test or be on the bench, but I said to him he had to work hard and earn the right to get into the team. I feel he has done that."
Care has leapt ahead of Dickson in the pecking order to earn a starting berth following injury to Youngs.
Dickson, a substitute in the first two Tests, was again among the replacements as Lancaster announced his side for the clash at Port Elizabeth's Nelson Mandela Bay Stadium.
In all, Lancaster has made six changes as he looks to secure a consolation win following defeats in Durban and Johannesburg.
Flanker James Haskell has also been given the chance to resurrect his international career in place of injured captain Chris Robshaw.
Haskell, who has 42 caps, has not played since last year's disastrous World Cup campaign after opting to broaden his experiences by playing club rugby in Japan and New Zealand.
The 27-year-old's return was made possible by his decision to rejoin former club Wasps next season.
Lancaster said: "I hadn't coached him before but he has been very positive, upbeat.
"He is an extrovert character but in a good way. He brings a lot of energy to the team.
"But energy is one thing and physicality is another and we are looking for him to bring that physicality to our back row as a defender and a ball-carrier."
Other changes see full-back Alex Goode and number eight Thomas Waldrom come in for their first Test starts.
Goode is accommodated by Ben Foden's switch back to the wing in place of David Strettle while Waldrom takes over from Ben Morgan.
Prop Alex Corbisiero, who established himself as first-choice loosehead in the Six Nations, returns after missing the end of the domestic season following a biceps operation and the start of the tour with a knee problem. Joe Marler drops to the bench.
Lock Tom Palmer comes in for Mouritz Botha while centre Brad Barritt, who needed stitches in his eyeball after the first Test, is back among the replacements. Hooker Dylan Hartley takes over as captain.
Goode, 24, will be England's third full-back of the series after the now injured Mike Brown and Foden and, as he is a former fly-half, Lancaster expects him to add dynamism.
Lancaster said: "It is a great opportunity for Alex to get his first start. He is a great footballer and understands the game well. I hope he will bring that to the party on Saturday."
Lancaster has earned plaudits for overseeing a transformation of the side since the World Cup and their fighting spirit has been in evidence during the series.
But Lancaster recognises a victory would represent a more tangible sign of progress.
He said: "I don't think there is such a thing as a dead rubber in international rugby. It is about winning the next game.
"We are desperate to go out there, get the win and finish the season on a high.
"We have got to be an 80-minute team. We have performed well in significant patches of both Tests but we have never had the complete 80 minutes."
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