Deshmukh, contesting as an independent, had lost to Congress's Raosaheb Shekhavat last time.
"I am going to join the BJP today and I have been assured ticket from Amravati seat. I am going to file my nomination papers tomorrow morning," he told PTI.
Two days ago, NCP's Surekha Thakare joined Shiv Sena. Another NCP leader Sulabhatai Khodke, who was expelled from the party during the last Lok Sabha elections, has joined Congress and been rewarded with candidature from Badnera.
In Melghat, BJP's Rajkumar Patel had switched over to NCP and will contest from there.
Dr Anil Bonde, sitting independent MLA from Morshi and a former Shiv Sena leader, has joined BJP.