The 35-year-old won 85 caps for his country, with the pinnacle of his stellar Springboks career coming when he helped them lift the Webb Ellis Cup in Paris seven years ago.
Botha also won the Rugby Championship and was part of the 2009 South Africa team that beat the British and Irish Lions 2-1.
His final appearance came as a replacement in last weekend's 31-28 victory over England at Twickenham, with Botha confirming his retirement immediately after the Springboks' 22-6 win over Italy on Saturday.
In a statement published on South Africa Rugby's official website, the Toulon man also revealed he plans to retire from all forms of the game in 2015.
"The news of my retirement will probably be described as sudden and unexpected, but it is a decision that I've been mulling over since 2011 [when he suffered an Achilles injury]," said Botha.
"My announcement is made retrospectively for good reasons. I didn't want to make this announcement before today's Test against Italy, as I didn't want to detract the focus of my team-mates from this very important match.
"Coach Heyneke [Meyer] was willing to pick me for this Test, but I requested him not to because I didn't want to make a big thing out of it.
"I wanted this Test to be about the Springboks and not about me. It is my decision because in my eyes, the team always comes first and I didn't want to be branded as arrogant and self-centred.
"To be able to make this decision on my own terms, knowing I'm still good enough to play Test rugby, is a huge blessing.
"I want to thank everyone involved in my career for the opportunities I was given, as well as the supporters of the teams I represented for staying loyal to me even when I let them down.
"I'm planning to finish my contract with Toulon and defend our titles this season.
"And who knows, perhaps there is a province in South Africa who can see me add value to their Currie Cup campaign next year and I can play my final match in my beloved country of birth before finally hanging up my boots at the end of 2015 at all levels of the game."