Williams was charged over an incident at a nightclub in his home town of Albany in WA's southwest in late December.
Police allege Williams, 19, got into an argument about 1.30am (WST) with a 29-year-old man.
The other man was ejected from the venue, and when Williams left he saw the man outside.
Williams then allegedly punched the man, who was taken to Albany Regional Hospital with a broken jaw.
The footballer was charged with assault occasioning bodily harm.
On Thursday in Albany Magistrates Court he pleaded not guilty via video link from Melbourne.
The case has been scheduled for mention in March.
The footballer asked to be excused from appearing via video link on that date, but the request was rejected by the court. No date for the trial has been set.
Despite the not guilty plea, the Magpies have chosen to make Williams work with the Salvation Army's soup van on the streets of Melbourne as punishment for his involvement in the late-night scuffle.
Collingwood coach Nathan Buckley announced last week Williams would help the Salvos for the next 10 weeks until the home-and-away season kicks off.
"We just feel it's a good opportunity for Marley to see a different side of things, and we'll be supporting him with our leaders attending each week as he goes through that community service, which we think is appropriate," Buckley said.
Williams joined the Magpies last year as a rookie and played six senior games. He has been promoted to the senior list.
