SEOUL, South Korea — Lee Myung-bak, a former president of South Korea, was sentenced on Friday to 15 years in prison for bribery and embezzlement, becoming the second South Korean leader convicted in recent months in a crackdown on corruption.

Mr. Lee was president from 2008 to 2013. His successor, Park Geun-hye, who was impeached and ousted on charges of corruption and abuse of power, was sentenced to 25 years in prison by an appeals court in August.

In a nationally televised ruling on Friday, Mr. Lee was convicted of collecting bribes from various sources, including 6.1 billion won, or about $5.4 million, from Samsung, the country’s largest business conglomerate, when he was a presidential candidate and after he took office in 2008.

In return for the bribes, Mr. Lee did favors for Samsung executives, including granting a presidential pardon to Lee Kun-hee, the company’s chairman, who was convicted of embezzlement and tax evasion in 2009, Judge Chung Kae-seon said in her ruling at the Seoul Central District Court on Friday.