The mall, once one of the Kenyan capital's most upmarket shopping centres, was devastated by an intense fire that broke out during the September 2013 attack by Al-Qaeda-linked Shebab gunmen that left at least 67 dead.
Since then, the bullet-scarred building has been empty.
But Westgate director Alex Trachtenberg, speaking at a prayer meeting on Tuesday, said tenants were returning and were expected to begin refitting stores ahead of a July opening.
Atul Shah, who heads the key regional supermarket chain Nakumatt -- whose store in the mall was where many of the victims were slaughtered -- said they were readying to reopen.
"The fall of Westgate following the attack two years ago was a big blow to our business," Shah said. "I am however glad to confirm that our customers, among other partners, have enabled us to overcome the challenges.