The boy from Brisbane, whose name has not been released, may be at significant risk, police say.
Cassandra Standley, 38, and Shannon Adams, 35, were seen with him on Bowen Street in Windsor on March 6 and reported missing to authorities today.
The pair is known to the child.
Initial investigations indicate the group could be in the Aspley area in the city’s north and police urge anyone with information to call 131 564, or to call triple-0 if it’s life-threatening.
The boy is described as Caucasian in appearance and is approximately 120cm tall, of a fair complexion and with short blonde hair.
The woman is described as Caucasian in appearance and is approximately 165cm tall, of a slim build and with light brown hair and brown eyes.
The man is described as Caucasian in appearance and is approximately 175cm tall, of a medium build and with short brown hair and blue eyes.
If you have information about the child call 131 564, or phone triple-0 if it’s life-threatening