The Supreme Court earlier also relaxed the mandatory wearing of coat and gown in the lower courts
To mark the day, black flags were hoisted in his village Kutubpur and at Shahid Smriti Bidyapith, a school founded by him, on Saturday morning.
Admirers also wore black badges and placed wreathes at the portrait of the creator of popular characters like Himu and Misir Ali.
Students and teachers of Shahid Smriti Bidyapith took out a mourning procession from the school premises.
A rally was held later at the school auditorium.
School Headmaster Asaduzzaman recalled life and works of the great author.
He vowed to project Humayun Ahmed’s literary works to the new generation.
Humayun Ahmed Smriti Sangsad also took out a mourning procession in Kendua Upazila Sadar.