The 32-year-old former Namibia captain has made 113 appearances since joining Sarries in 2009 and helped the club win two Premiership titles.
Burger, who won 41 caps and appeared at the 2015 World Cup, will return to Namibia to become a farmer.
"It is sad that it's coming to an end but playing rugby is something that I have really loved doing," he said.
"Growing up I wanted to be a professional rugby player and I have been fortunate to live that dream."
Saracens director of rugby Mark McCall described Burger, who leaves just two weeks before the Champions Cup final and the start of Sarries' Premiership play-off campaign, as "an amazing player and person".
"He set a phenomenal example on the field with his bravery and the way that he gave everything he could in every game," McCall told the club website.
"He will always be remembered as one of the true greats of Saracens."

15 May 2017 Last updated at 13:14 BST
The narwhal is a mysterious member of the whale family that mostly lives in the Arctic.
It has a long pointy tusk that points out of the end of its nose - that's led to the creature having the nickname, the "unicorn whale".
Scientist knew very little about what these tusks were for until they started filming them in the wild, using drones.
Now they know it's part of a clever way to hunt fish...
Watch this...

The Labour leader said a new law would allow family and friends of deceased men to seek the quashing of historical convictions for "gross indecency".
Legislation would be known as "Turing's Law" in memory of Alan Turing, he said.
The Enigma code-breaker was convicted of "gross indecency" in 1952 and was only given a posthumous pardon in 2013.
Homosexuality was illegal until it was decriminalised in England in 1967.
Mr Turing was convicted for gross indecency in 1952 in connection with an affair with a 19-year-old man, after which he was chemically castrated.
The conviction meant he lost his security clearance and had to stop the code-cracking work that had proved vital to the Allies in World War Two.
The mathematician was only given a royal pardon in 2013, nearly 60 years after his death by suicide in 1954. This followed an official apology by former prime minister Gordon Brown in 2009 for how Mr Turing had been treated.
Relatives of Mr Turing have led a high-profile campaign to secure pardons for the 49,000 other men convicted under historical indecency laws.
Announcing his support for the move, Mr Miliband said: "What was right for Alan Turing's family should be right for other families as well.
"The next Labour government will extend the right individuals already have to overturn convictions that society now see as grossly unfair to the relatives of those convicted who have passed away."
Asked whether David Cameron would back Mr Miliband's proposals, No 10 said the prime minister "will always continue to look carefully at what more can be done to right these wrongs".
A spokesman pointed out that the coalition government had already passed legislation to allow individuals with historical convictions or cautions for certain homosexual activities to apply for them to be removed from criminal records.
"It was this government that introduced that 2012 act," said the spokesman. "It was under this government that Mr Turing received the pardon through the use of the royal prerogative."
A pardon is only normally granted when the person is innocent of the offence and where a request has been made by someone with a vested interest such as a family member.
But, in Mr Turing's case, a pardon was issued without either requirement being met, after an intervention by Lord Chancellor Chris Grayling.
Saracens back row Jacques Burger will retire from rugby after Sunday's Premiership game against Newcastle.
[NEXT_CONCEPT]
Scientists reckon they've figured out why the narwhal has its famous tusk.
[NEXT_CONCEPT]
A future Labour government would pave the way for posthumous pardons for gay men convicted under historical indecency laws, Ed Miliband has said.