Devotees offered prayers at mosques and specially arranged Eid-gahs across the state in the morning.
Special sermons were held in many mosques, where religious leaders urged devotees to uphold values of compassion, fraternity and social harmony.
Traditional feasts were prepared in Muslim houses with an array of ethnic delicacies.
Kerala government had declared public holiday for all state-run offices and educational institutions today.
Governor Justice (Rtd) P Sathasivam, Chief Minister Pinarayi Vijayan and opposition leader in the assembly Ramesh Chennithala extended Eid-ul-fitr greetings to Muslims across the state.
He also wished that the celebration may brighten the world with love, harmony and brotherhood.
"May Eid-ul-fitr brightens our world with love, harmony and brotherhood through its unmatched message of self-discipline, sacrifice and charity," the Governor said.