The grim image was joined by a banner adorned in the red and white of Atletico flung over the same bridge, which read: "Madrid hates Real".
In response to news, both Atletico and La Liga have come out in condemnation of such vile acts.
"Acts like this are absolutely repugnant and inadmissible and shame society. Our condemnation to any act that attacks the dignity of people or institutions is categorical and unreserved," Atletico's official statement read on the club's website. "The rivalry between the two clubs is at its maximum, but so is respect. No individual, whatever their intentions or colours, can stain the coexistence between different fans."
Spanish football's governing body added in a Tweet: "LaLiga strongly condemns acts of hatred and intimidation against [Vinicius Junior]. LaLiga, as in the past, will press for an investigation into the matter by relevant state security forces and bodies, seeking convictions for those responsible and requesting the most severe sentences."
The controversy comes as the local rivals come head-to-head in the Copa del Rey quarter-finals on Thursday. Meetings between the two biggest sides in Spain's capital have always produced fiery affairs, although recent games have taken on a rather unsavoury tone, with Vinicius on the receiving end of vile taunts.
The Brazilian, who has struggled to match his 2021-22 form so far this campaign, was subject to racist abuse the last time the two sides met in September.
Footage of supporters chanting "Vinicius is a monkey" was captured outside the stadium, while monkey noises were audible every time the Brazilian touched the ball at the Wanda Metropolitano.
Vinicius later hit out at the racist abuse received, calling for lifetime bans of those found guilty.