SEOUL, South Korea — Park Geun-hye, South Korea’s impeached and ousted president, was sentenced Friday to 25 years in prison, as an appeals court convicted her of collecting more bribes than previously believed from Samsung, the country’s largest business conglomerate.

In a lower-court ruling in April, Ms. Park, 66, was sentenced to 24 years in prison on bribery, extortion, abuse of power and other criminal charges and ordered to pay 18 billion won ($16 million) in fines. But on Friday, the appeals court in Seoul added another year to her prison term and increased her fine to 20 billion won, saying that the collusive ties between Ms. Park and Samsung were more expansive than the lower court had ruled.

Ms. Park, who has been in jail since last year, did not appear in court on Friday to hear the verdict. Her trial does not end until the Supreme Court rules on the case.

Ms. Park’s fall from power began in 2016, when hundreds of thousands of protesters began months of weekly rallies in central Seoul demanding that she be forced from office. That December, the National Assembly impeached her on charges of bribery and abuse of presidential power. In March 2017, Ms. Park became the first South Korean leader removed from office through parliamentary impeachment after the Constitutional Court upheld the lawmakers’ decision.