The 42-year-old has been linked with a number of roles since guiding England to the semi-finals of the recent World Cup, where they lost in dramatic fashion to New Zealand.
According to Sky Sports News, the former Bradford Bulls boss will fill the void left by Paul Green, who left Allianz Stadium to become head coach at North Queensland.
McNamara said after England's recent defeat to New Zealand that he would like to stay on, and it is still unclear as to whether he will continue in the job.
An announcement is expected later on today.
The Roosters, spearheaded by the Rugby League International Federation's Player of the Year, Sonny Bill Williams, won their first title since 2002 this year.