Incumbent President Mohamed Abdullahi Farmaajo is to hand over power to his successor on Sunday, May 22.
Farmaajo lost the May 15 elections to Hassan Sheikh Mohamud.
Mohamud had initially led the country from 2012 to 2017 before losing to Farmaajo.
Legislators from both chambers of the federal parliament voted for Mohamud after three rounds of voting last Sunday.
On May 21, the two leaders toured Villa Somalia where the Office of the President is located.
The handing-over ceremony would mark the end of the electioneering period in Somalia, which has lasted more than two years.