Confirming the news to People, a source said of Khloé Kardashian’s troubled husband, "He realised he needs help".
Lamar’s decision to seek help comes at a crucial time.
Last week the 33-year-old basketball star was arrested for driving under the influence. According to an incident report, Lamar showed "signs of intoxication and was unable to perform field sobriety tests as explained and demonstrated."
He then refused to take a chemical test, resulting in the suspension of his license for one full year.
Lamar's marriage to reality star Khloé, 29, has also been put under immense strain.
The once blissful couple, who are due to celebrate their four year wedding anniversary on 27 September, haven't been pictured together since 2 June. But both are still wearing their wedding rings – and Khloé is said to determined to help her husband get his life back on track as he struggles to overcome his issues.
She has so far refused to directly comment on continued speculation about her private life, including Lamar’s alleged infidelities and his recent arrest.
But on Sunday, she posted a message to her Twitter followers that read, "As much as I wish I were made of steel… I’m not. I'm pretty damn close to it though hehe."
The following day she uploaded a photograph that showed her posing with friends infront of an illuminated sign that read "todo es possible" (everything is possible).
Lamar has admitted to drug use in the past. He violated NBA drug policies twice in eight months back in 2001, and in 2003 spoke about his marijuana use.
"I just couldn't control myself living in LA," said the star. "The lifestyle that I was living and the things I had access to."
His own father struggled with heroin addiction, and Lamar has said he wondered whether he was "fighting my father's demons."