The front page of Thursday's edition of The Sun showed the 24-year-old England international wearing a head dress and items resembling a mock circuit board, mobile phone and cables on his chest. He was also wearing bottles of the liqueur Jagermeister and the energy drink Red Bull.
A blend of the two drinks is known as a 'Jagerbomb' and Smalling's management company on Thursday morning insisted the player's outfit, worn at a private party, had simply been an "attempted comedy play" on the drink.
In a statement, Smalling's management company the Wasserman Media Group said: "Chris and his girlfriend hosted a fancy dress party to celebrate Christmas and their belated birthdays with close friends in the assumed privacy of his own home.
"He dressed in a costume consisting of empty bottles of jagermeister and cans of Red Bull strapped to his chest in an attempted comedy play on the popular 'jager bomb drink'.
"Although he fully accepts in hindsight it was an ill-thought out and insensitive decision, absolutely no harm was intended whatsoever and he apologises for any offence caused."