The Senate, dominated by opponents of President Macky Sall, had voted against its own demise last week but its decision was superseded earlier this week by that of the lower house, which supports the move.
In a session of both houses on Wednesday, more than two thirds of lawmakers approved the suppression of the Senate with immediate effect.
Sall last month announced emergency legislation to scrap the Senate and turn over its annual budget of almost eight billion CFA francs (12 million euros, $16 million) to dealing with the impact of deadly floods.
At least 13 people have been killed in several weeks of flooding and thousands left homeless.
The post of vice-president, created in June 2009 by former president Abdoulaye Wade but never filled, was allocated an annual budget of more than two billion CFA francs (three million euros).
The institution was strongly criticised in June 2011 when Wade introduced a bill stating that if the president resigned, died or was unable to carry out his duties, he would be replaced by the vice-president.
Many of Wade’s critics claimed he was setting up a system for his son Karim, who held a ministerial post, to succeed him, but Wade denied having such “monarchical” plans.
He was defeated at the polls by Sall in March after 12 years in office.
With the Senate’s disappearance, the National Assembly remains the only legislative body.