SEOUL, South Korea — Park Geun-hye, South Korea’s impeached and ousted president, was sentenced on Friday to 24 years in prison on bribery and other charges in a case that exposed the entrenched, collusive ties between the government and huge conglomerates like Samsung.

The conviction and sentencing represented a climactic moment in an influence-peddling scandal that drew hundreds of thousands of South Koreans into the streets demanding Ms. Park’s resignation and shook the country’s political and business worlds.

Ms. Park — the conservative daughter of a past dictator — is the country’s first former leader to be convicted of crimes since two former military-backed presidents were found guilty of sedition and corruption in the 1990s. Ms. Park’s conviction on bribery, coercion, abuse of power and other charges was the first lower-court ruling on a criminal case to be broadcast live in South Korea.

Many viewed her conviction as a giant step forward for South Korea’s democracy, raising hopes that the country would tackle the corruption that accompanied its impressive economic rise. But there are fears that no true reform is possible until the country’s powerful conglomerates are held to better account for serious white-collar crimes like bribery.