The state-run Bahrain News Agency says the court on Wednesday backed the verdicts, which were issued in June. International rights groups have denounced the verdicts.
The activists include eight well-known political figures sentenced to life in prison after being charged with trying to topple the Gulf kingdom’s ruling Sunni dynasty. Thirteen others received lesser sentences. Some were sentenced in absentia.
Bahrain’s majority Shiites began protests in February seeking greater rights. Authorities have responded with sweeping crackdowns, including hundreds of arrests.