Around 86 percent of foreign workers in the Kingdom are earning less than SR 2,000, says a study conducted by the Ministry of Labor.
The study estimates the number of foreign workers in the Kingdom at around 9.2 million.
The findings came as authorities stepped up their campaign to regularize the status of undocumented migrant workers in Saudi Arabia.
Custodian of the Two Holy Mosques King Abdullah had initially ordered the Ministry of Interior and the Ministry of Labor to give a three-month grace period to expatriates violating labor regulations.
Another royal decree later extended it to the end of the Hijri year following many requests from businessmen and diplomatic missions.
As many as 1.6 million expatriates have legalized their status so far.
Expatriates account for 31 percent of the total population of Saudi Arabia working in the private sector and occupy 42 percent of jobs, excluding domestic workers, said the survey, carried out by a center specialized in labor studies.
The study revealed a 12-percent unemployment rate among citizens.
Around 32 percent of those employed are college graduates, and 68 percent have reached high school level or less.
The private sector provided Saudi nationals with 3 million jobs between 2008-2013.
Khalaf Al-Otaibi, head of the international commercial and industrial union, said more than two million expatriates were not able to legalize their status before the end of the first grace period.
He stressed the need to extend working hours and to open more labor offices and passport department branches to address the crisis.