The 27-year-old was shot dead by Gardaí on December 30 last year on the front porch of his house in Clonee in west Dublin.
It followed a stand-off with officers, during which Mr Nkencho refused to drop a kitchen knife.
Gardaí said at the time that they had unsuccessfully attempted to use non-lethal force before he was fatally injured.
The anniversary event is being organised by YARI (Youth Against Racism & Inequality) and the Justice for George Nkencho campaign for Thursday, December 30.
Participants are encouraged to gather at 6pm outside St Brigid's Church before taking part in a walk to Blanchardstown Garda Station.
A Facebook post states that on December 30, 2020 George Nkencho “became the first black man to be killed by Irish police, in the midst of a mental health crisis and on his own doorstep".
“The Nkencho family now call on all young people, activist groups, trade unions, and members of the Dublin 15 community to remember George - a son, brother, friend, footballer and caring member of his community."
The post also calls for a full and thorough investigation into George's killing and that gardaí are held “fully accountable to the communities they serve”.
It also demands training and provision of resources for gardaí to deescalate mental health crises.
“Support the Nkencho family in their search for justice by joining a candlelit walk to say ‘Never Again’, meeting at 6pm outside St Brigid's Church and walking to Blanchardstown Garda Station on Thursday, December 30,” it adds.
Earlier this week, his family was meeting the Garda watchdog as part of the investigation into his death.
The Garda Ombudsman is looking into the case and will decide if gardaí have a case to answer.
Solicitor Phelim O'Neill said he was meeting GSOC investigators, along with the Nkencho family. "We expect to get an update on how the investigation is progressing and confirmation that the investigation will be concluded by the anniversary of George's death,” he said.
An inquest into the 27 year-old's death opened in June. It's due to get back underway on December 14.