Three Congress MLAs and one Samajwadi Party MLA switched to the Bahujan Samaj Party on Wednesday.
On Tuesday, BSP leader Swamy Prasad Maurya joined the BJP.
BSP leader Naseemuddin told reporters that Nawab Qazim Ali and Mohammad Muslim, legislators from Swar in Rampur district and Tiloi in Amethi, had joined the BSP unconditionally.
They are likely to get BSP ticket to contest Assembly elections due next year.
Dilnawaz Khan, a Congress MLA from Bulandshahr, Samajwadi Party legislator from Budhana (Muzaffarnagar) Nawazish Aalam Khan and former BJP minister Avdesh Verma have also joined the BSP, Naseemuddin said.