Cahill is reportedly flying to England this weekend to secure a return to the club where he began his senior professional career in 1998.
The Lions had publicly played down the prospect of a deal for the 38-year-old, a fans’ favourite at The Den, when rumors of a possible Millwall return for Cahill first emerged earlier this month.
Cahill, 38, walked out of A-League outfit Melbourne City last December.
The South London Press, citing sources, says Cahill will finalise his return to Millwall at meetings this weekend.
"Lions boss Neil Harris ... is very keen to add him to his squad for the Championship run-in," the South London Press is reporting.
"... He is expected to jet over so that the finer details of his switch can be wrapped up."
Harris is a former Millwall teammate of Cahill, who is desperate to find another club to press his claims to play at a fourth World Cup this year.
Cahill scored 57 goals in 242 games with Millwall before transferring to the Premier League in 2004, where he spent eight seasons with Everton.
Stints with New York Red Bulls, Shanghai Shenhua and Hangzhou Greentown followed before he returned to Australia and Melbourne City in 2016.
