KPMG on Wednesday said it has fully exited Russia and Belarus amid the invasion of Ukraine, about three months after announcing plans to do so. The move follows Deloitte’s, which exited those countries last month.

“The Russia and Belarus firms have formally left the network and ceased to be KPMG member firms” on Wednesday, a KPMG spokesman said. “This means KPMG no longer has a firm in Russia or Belarus.”

The Big Four accounting firms—which also include PricewaterhouseCoopers and Ernst & Young—in March said they would leave the country and began disentangling knotty relationships with their counterparts there. Deloitte, a sponsor of CFO Journal, on May 24 said it completed its exit from Russia and Belarus.

On Tuesday, PwC said it continues to work on aspects of its Russian firm’s departure from the company’s global network. On April 29, the company said the PwC Russia brand had separated from the network.

EY’s Russian website as of Wednesday said the Russian firms are in the process of separating from the company’s world network.

In March, KPMG said it employed more than 4,500 people in Russia and Belarus. The firm had operated in Russia for about 30 years.

The Big Four face difficulties in making clean exits from Russia because of the way their global networks are structured. Firms in each country are separately-owned entities, bound by a legal agreement under which they pay a fee to share branding, technology and intellectual property.

KPMG, which hasn’t broken down its revenue from Russia or Belarus, reported $32.1 billion in global revenue for the fiscal year ended Sept. 30, 2021, up 10% from the previous year. That includes $14.3 billion generated in Europe, Middle East and Africa.

Write to Mark Maurer at Mark.Maurer@wsj.com