A Marcus Smith penalty two minutes from time sealed a 27-26 win for the Red Rose against the reigning world champions.
It was a memorable afternoon at Twickenham, particularly for Saints star Lawes, who was captaining his country for the second time.
He has won both games in which he has led England this autumn, and the Saints star couldn't have been happier with how things ended against the Springboks.
"I'm very proud," Lawes said.
"I said to the boys on the night before the game how proud I was to be able to lead them out and I couldn't be happier with the buy-in from the guys.
"The only reason we won that game was because we were really fighting for each other - and that showed out there on the pitch.
"We made it very hard for ourselves and we left a lot of points out there, but we can build from that, definitely."
Harlequins fly-half Smith held his nerve to slot the winning penalty to ensure England would end the Autumn Nations Series with a 100 per cent record.
And Lawes said: "That's why he gets paid the big bucks!
"He slotted it easily, no worries, like being back on the training pitch.
"We still had a bit of a job to do after it went over because they had a kick-off, but I really thought we were going to win the game.
"I'm incredibly happy we were able to put a performance in like that.
"In the first half you saw what happens when we put our game together.
"In the second half we gave away penalties and there were little things we didn't need to do, which let them play their game.
"We had to stick in the fight, which we just about managed to do, and then we put a try on them and sealed the win with that Marcus kick."
Elsewhere, Dan Biggar kicked four penalties and two conversions as Wales claimed a dramatic 29-28 win against Australia in Cardiff.
Sam Matavesi, Api Ratuniyarawa and Frank Lomani started for Fiji as they finished their autumn campaign with a 15-15 draw against Georgia in Madrid.
Saints will get all of their international players back this week as they prepare to face Bristol Bears in a Gallagher Premiership game at Ashton Gate on Friday night.