Police vehicles and motorcycle outriders were parked nearby. Senior government officials told AFP that ambassador Kang Chol was expected to leave Malaysia at 18.25 (1025 GMT) on flight MH360 for Beijing, shortly after the deadline for his expulsion expires.
Malaysia and North Korea are enbroiled in an acrimonious dispute over the murder of Kim Jong-Nam, the estranged half-brother of Pyongyang's leader, at Kuala Lumpur International Airport last month.
North Korea has not acknowledged the dead man's identity but has repeatedly disparaged the murder investigation, accusing Malaysia of conniving with its enemies.
Asked by reporters whether he would demand an apology from Pyongyang, Prime Minister Najib Razak replied: "Right now we are not getting anything. I don't expect anything."
More From This Section
"They should have apologised based on principles, (so) we have declared him persona non grata," he told reporters.
The diplomatic dispute erupted last month when Malaysian police rejected North Korean diplomats' demands to hand over Kim's body.
Kang then claimed the investigation was politically motivated and said Kuala Lumpur was conspiring with "hostile forces", referring to the North's arch-rival, Seoul.
Malaysia summoned Kang for a dressing-down, with Najib saying the ambassador's statement was "diplomatically rude".
Malaysia has also recalled its envoy to Pyongyang and cancelled a rare visa-free travel deal with North Korea. It issued a February 28 deadline for an apology.
The foreign ministry has said the expulsion is "part of the process by the Malaysian government to review its relations" with North Korea.
Police are seeking seven North Korean suspects in their probe, four of whom left Malaysia on the day of the murder. But on Friday they released the only North Korean they had arrested for lack of evidence.
After Ri Jong-Chol was deported, he claimed police offered him a comfortable life in Malaysia for a false confession, saying the investigation was "a conspiracy to impair the dignity of the Republic (North Korea)".