The Customary Land Rights Act and the Land Commission Act, both enacted on Monday, empower local landowners to negotiate the value of their land with investors and prevent it being leased out without their express consent.
One of the laws will also end a colonial-era provision that bars descendants of freed slaves from owning land outside the capital, Freetown.
Campaigners and locals praised the move, while one palm oil company executive said it would spell the end of investment.
A director of SOCFIN , the biggest agribusiness company in Sierra Leone, called it a "dream of NGOs".
"Certainly it will block any investment... It makes things very expensive and we are all prone to enormous blackmail by various communities," Gerben Haringsma added.
The Luxembourg-based company has invested more than $150 million in palm oil farming in Sierra Leone. It has also frequently clashed with local landowners.
The West African country has a history of sometimes deadly conflict between local communities and foreign companies that have cleared huge tracts of land for palm oil and sugarcane plantations in recent years.
Locals have complained of environmental damage, losing their livelihoods and not being fairly compensated for their land. Under the current system, landowners get an annual rent of $2.5 per acre, which was determined by the state.
"To our knowledge there is not a legal regime anywhere, in either hemisphere that grants such robust rights to communities facing harm," said Eleanor Thompson of Namati, an international legal advocacy group.
Lands Minister Turad Senessie said the new laws would encourage investment by ensuring peace and order.
"This is a win-win situation for both business and Sierra Leoneans including rural landowners," he told Reuters.