Brodie Jake Dewar entered the plea during his first appearance in the West Australian Supreme Court on Monday.
The 21-year-old, who is on bail, allegedly bashed Mr Picton, 36, in Northbridge, in Perth's inner city, in the early hours of December 27.
His case was listed for a 10-day trial in the Supreme Court beginning July 20, 2027.
The matter will return to court for a mention on October 7 and again on December 7 for a half-day hearing over the admissibility of some evidence.
Dewar's family and friends were in court for the brief hearing, as was Mr Picton's widow Priya Brown.
Her husband's death triggered an outpouring of grief from his family, friends and colleagues, as tributes flowed from the prime minister, several premiers and business leaders.
Mr Picton, who has been lauded as a brilliant political tactician, had advised state and federal politicians and helped guide WA Labor to a landslide 2021 election victory.
His older brother Chris is a senior minister in the South Australia Labor government.
A Perth court has previously heard Dewar and Mr Picton came face-to-face outside the Paramount Nightclub after an incident inside the venue.
Dewar allegedly struck Mr Picton in the face, and he fell to the ground, hitting his head on the pavement.
Mr Picton died in hospital several weeks later.
The incident was recorded on CCTV.
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