The Mandika-language phrase can be translated as “chief bridge builder” or “conqueror of rivers”.
A statement from the presidency said Mr Jammeh should now be known as “His Excellency Sheikh Professor Alhaji Dr Yahya AJJ Jammeh Babili Mansa”.
He had taken the title once before, in 2014, only to drop it four months later, the Point newspaper reports.
President Jammeh seized power in 1994 as a young army lieutenant and has won four widely criticised multi-party elections since then and faced down several coup attempts.
He told the BBC in 2011 that he would rule for “one billion years… if Allah says so”.