The three are accused of violently robbing Mr Muriuki of Sh100,000 and injuring him at Hotel Boulevard in Nairobi.
MP Simon Mbugua and two others have been freed on Sh200,000 cash bail each after denying robbery with violence charges against a city trader.
The East African Legislative Assembly (EALA) lawmaker was charged with violently robbing Mr Timothy Muriuki of Sh100,000 alongside Mr Anthony Otieno Ombok, alias Jamal, and Mr Benjamin Odhiambo Onyango, alias Odhis, and others not before the court.
Senior Principal Magistrate Martha Mutuku also ordered the trio to deposit their identity cards in court and set hearing of the case for July 18 this year.
The three are accused of robbing Mr Muriuki and injuring him at Hotel Boulevard in Nairobi when goons interrupted his press conference last week.
Mr Mbugua was arrested on Tuesday together with three other suspects in connection to the attack.
One of the suspects arrested on Tuesday, Mr Stephen Sangira, was not charged as the police said they found no evidence linking him to the incident.
The four were arrested at the Sagret Hotel and were taken to the Central Police Station in Nairobi where they were detained until 6am Wednesday when they were taken to court.