The 21-year-old appeared fit and started the session in a fitness drill alongside new signing Ben Hunt.
It was the first first field session Mam had attended since being suspended for nine matches and fined $120,000 by the NRL and Broncos after he pleaded guilty to a drug driving charge in December.
Mam will continue to train with the Broncos from now on but will not be available to make his NRL return until Brisbane's round 10 clash with South Sydney.
He will also not play in the Queensland Cup competition.
Mam has been working at a building site since he came out of a rehab facility and will continue to do so on his days off.
AAP attended Tuesday's afternoon session, where Mam also worked closely with Hunt and attack coach Trent Barrett in kicking and passing drills before a ball work session.
Hunt, 34, is going to be a vital component at Broncos training in the next month as captain Adam Reynolds continues his rehabilitation from pre-Christmas neck surgery.
Hunt looked in peak condition at training and put on a clinic with his kicking drills. He trained in the halves and at hooker when the squad did ball work.
Mam was fined $850 and disqualified from driving for nine months after pleading guilty in court. (Russell Freeman/AAP PHOTOS)
His presence clearly gave the session clarity, just as he will need to do when he partners Reynolds in the halves in the NRL until Mam returns.
Former St George Illawarra captain Hunt, who played 187 NRL games for the Broncos from 2009-2017, is expected to play his first game for the Broncos in the NRL Pre-season Challenge in February against Canterbury.
Reynolds, who has a running joke that he "doesn't play trials", is also slated to make a rare appearance and partner him in that fixture.
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