The Syrian Arab Red Crescent (SARC) and the International Committee of the Red Cross confirmed the volunteer's death in Wednesday's incident.
"One SARC staff member was killed. Seven SARC volunteers and staff were injured, three of them severely," a statement said.
"Two beneficiaries who had come to the centre to receive humanitarian aid also died, and several others were injured."
The Britain-based Syrian Observatory for Human Rights monitor identified those two killed as a woman and a child.
The rocket fire hit a SARC distribution centre in the Hamdaniyah neighbourhood of the city, which was fully recaptured by government forces in December after a months-long siege and heavy fighting.
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The Observatory also reported five children were killed Wednesday when unexploded ordnance detonated in the Bustan al-Qasr neighbourhood, a rebel-held district recaptured by government forces in December.
Families who fled formerly rebel-held east Aleppo during the fighting in December, or earlier, have been returning to devastated neighbourhoods like Bustan al-Qasr to start the slow work of rebuilding.
Syrian government forces have carried out operations to clear explosives from east Aleppo and authorities have encouraged civilians to return to their homes.
Aleppo was once Syria's economic powerhouse and a tourist draw for its ancient markets and famed citadel.
But it was ravaged by fighting from mid-2012, when rebels seized the eastern portion of the city.
Years of conflict ended after a devastating siege and heavy assault saw government forces reclaim full control of Aleppo on December 22.
More than 310,000 people have been killed since the Syrian conflict began with anti-government demonstrations in March 2011.