The deal is Maybank's third acquisition in two months as it seeks higher-growth markets as its domestic market becomes more mature and competitive.
"This acquisition ... will align Maybank with a highly attractive franchise in a high-growth and under-penetrated banking market with a large population," Maybank Chairman Mohamed Basir Ahmad said in a statement.
Pakistan's banking industry is among the world's most profitable because of five years of financial reform, economic growth and rising incomes.
But banking analysts say Maybank is having to pay a high price for being among the last to hit the overseas acquisition trail.
Maybank's offer represents about 5.4 times MCB's book value, according to Reuters data.
That is toward the top end of recent deals in Pakistan, a magnet for foreign banks even before February's polls.
Oman's Bank Muscat and Japan's Nomura Holdings paid 2.8 times book value for Pakistan's Saudi Pak Bank in January this year. In 2006, Standard Chartered paid a a lofty 5.6 times for Union Bank.
Maybank voiced confidence in Pakistan's political outlook after February elections returned the nation to civilian democratic rule for the first time in almost a decade. Pakistan, a key U.S. ally, also sits on the front line of conflict between Western forces and Islamist militants.
"The political reform process has been underway and has already produced several important changes, including peaceful elections in February," it said in presentation material.
Flurry Of Deals, But Prices High
Maybank said on March 21 it had bought a 15 percent stake in Vietnam's An Binh Bank for $135 million cash.
A week later, it paid $2.7 billion or 4.6 times book value for a controlling stake in Indonesia's sixth-largest bank, Bank Internasional Indonesia -- a price judged very high by analysts familiar with BII.
Maybank shares have fallen 11 percent since the Indonesian deal was announced. Credit-rating agencies Fitch and Moody's have both put its ratings on a negative outlook, amid expectations that it would need to raise funds to bolster its balance sheet.
The stock was suspended on Friday, pending the MCB announcement. It last traded at 8 ringgit per share.
Maybank said it was buying the MCB stake from existing shareholders, including individual investors Mian Umer Mansha, Mian Hasan Mansha and Muhammad Saleem.
Other sellers were the bank's pension funds as well as the Nishat Mills Employees Provident Fund Trust and the Adamjee Insurance Company.
The deal included the possibility of buying up to another 5 percent of MCB Bank from the three individual investors. Under a separate agreement with the trio, Maybank would buy the additional shares at no more than 510 rupees per share.
Maybank stock was suspended on Friday, pending the MCB announcement. It last traded at 8 ringgit per share, giving it a total market value of nearly $12.4 billion. MCB had total assets of about 400 billion rupees ($6.14 billion) at the end of March.