The 22-year old, Hussein al-Saket, was found guilty of abducting, raping and murdering a four-year-old girl, who he later buried, said Rajeh Ezzedine, a judge who attended the execution.
Ali Ayedh, the victim’s uncle, said Saket “took part in the search for the girl before being unmasked” during the police investigation.
He said his public execution would act as a “deterrent for criminals”.
Saket was placed face down on Tahrir square in Sanaa, which the Shiite Huthi rebels have controlled since 2014.
A policeman shot him dead through the back with five bullets aiming for the heart, before his body was strung up on the end of a crane.