Mr Lawan polled 79 votes to beat his closest rival, Ali Ndume, who garnered 28 votes.
The Election of Senate President was held at the first session of the Senate on Tuesday.
After a secret ballot voting, the clerk to the National Assembly, Mohammed Sani-Omolori, announced Mr Lawan’s victory to the cheers of Senators and others in the chamber.
Mr Sani-Omolori said 107 senators cast their votes.
“It is my pleasure to announce that Senator elect, Ahmed Lawan, having scored the highest number of total votes cast is hereby returned duly elected as Senate President of the Federal Republic of Nigeria,” he said.
Former Senate Leader, Mr Lawan is the favoured candidate of the All Progressives Congress(APC).
His nomination was moved in a motion by Senator Yahaya Abdullahi and seconded by Adeola Olamilaken of Lagos West.
In related development, Delta Central Senator, Ovie Omo-Agege, has emerged Deputy President of the Nigerian Senate, upon allegations that he led thugs to steal the senate mace in 2018. He defeated immediate past Deputy Senate President, Ike Ekweremadu.
Mr Omo-Agege polled 68 votes while Mr Ekweremadu garnered 37. There was one void vote.
Earlier in the week, the ruling All Progressives Congress (APC) announced its choices of candidates for Deputy Senate President and Deputy Speaker.
The party adopted Mr Omo-Agege as Deputy Senate President, and Idris Wase, representing Wase Federal Constituency, for Deputy Speaker.
The decision was communicated to journalists in a statement signed by the party’s National Publicity Secretary, Lanre Issa-Onilu.
“The National Working Committee (NWC) of APC held emergency meetings Saturday 8 and Sunday 9 of June 2019.