The law sets a minimum age of 18 for household work, in a bid to end the exploitation and abuse of young girls working for unscrupulous employers.
Passed in 2016 following years of debate, it imposes financial penalties on employers failing to provide contracts, a minimum wage, a weekly day off and annual holidays.
The government at the time hailed the law as major progress.
However, human rights say it does not go far enough, allowing 16-17 year-olds to work as domestic helpers for a further five years until October 2023.
Thousands of young girls in the North African kingdom are employed as maids, often facing abuse from their employers.
The Moroccan Collective for Eradicating the Exploitation of “Little Maids”, as the young housemaids are known, said the new law fails to provide means to reintegrate them into society.
There are no official figures on the number of minors employed as domestic maids in Morocco, who often hail from impoverished rural backgrounds.
A 2010 study commissioned by NGOs found that between 66 000 and 80 000 girls under 15 years old were working as maids in Morocco.