BANGKOK — Thailand’s Supreme Court on Tuesday ordered former prime minister Thaksin Shinawatra to serve a one-year prison term after upholding convictions for graft and abuse of power, court officials and reports said.

The ruling, issued by the nation’s highest court, finalizes sentences in long-standing cases against Thaksin related to official misconduct. The decision leaves him subject to immediate custody under Thai law, court officials said.

The verdict closes a chapter in legal proceedings that have shadowed Thaksin since he first rose to national prominence. The convictions, for graft and abuse of power, were reviewed by appellate courts before reaching the Supreme Court. Under Thai judicial procedure, a Supreme Court decision is final and cannot be appealed.

Thaksin, a former telecommunications entrepreneur who served as prime minister in the 2000s, has remained a central and polarizing figure in Thai politics for years. His supporters credit his policies with improving the livelihoods of many rural voters, while critics and successive judicial and military interventions have accused him of corruption and undermining democratic institutions.

The Supreme Court’s ruling is likely to reverberate through Thailand’s political landscape, where parties and movements aligned with or against Thaksin have shaped governments, protests and policy debates. The one-year sentence marks a legally definitive moment in a broader political saga that has included coups, mass demonstrations and multiple court cases.

Officials did not immediately provide details on when authorities would take Thaksin into custody to begin serving the sentence, or whether any administrative processes, such as transfers to prison facilities or notifications to law enforcement agencies, would precede that step. The timing and logistics of imprisonment typically involve coordination between the judiciary, prison authorities and police.

Domestic reactions were mixed in initial reporting. Supporters of Thaksin have historically mobilized to protest actions they view as politically motivated, while opponents have typically welcomed judicial rulings against him as upholding the rule of law. How political parties, social movements and business interests will respond to the court’s latest decision remains to be seen.

The ruling underscores the judiciary’s continuing role in adjudicating high-profile political figures in Thailand. It may also influence upcoming political maneuvers, party strategies and public debate as actors across the political spectrum react to the legal resolution of one of the country’s most consequential political figures.

Further reporting will aim to provide details on the implementation of the sentence, any official statements from Thaksin or his legal representatives, and responses from political parties and civil society in Thailand.