At the start of the session, Speaker Femi Gbajabiamila read their letters of desertion.
Sani Dan-Galadima had announced his defection in the chamber earlier on Wednesday.
On Tuesday last week, Governor Bello Matawalle of Zamfara State, together with members of the federal and state legislatures, publicly declared his defection from the PDP to the APC in Gusau, the state capital.
All 24 members of the state House of Assembly, all three senators, and six of the seven members of the House of Representatives had joined the ruling party after the governor.
However, Aliyu Gusau, the Deputy Governor, and Kabiru Mafara, a member of the House of Representatives for the Anka/Talata-Mafara Federal Constituency, have remained in the PDP.
Senator Hassan Gusau, who represents Zamfara Central Senatorial District, announced his departure from the PDP in plenary on Tuesday last week.
Gusau’s letter alerting his colleagues of his action during the plenary was read by Senate President Ahmad Lawan.