Ray, who was earlier suspended from the BJD, joined BJP along with his supporters in the presence of state party president K V Singhdeo, Union Minister Dharmendra Pradhan, party's Odisha in-charge Arun Singh and senior leaders.
Singhdeo formally announced the entry of the ex-MP into the BJP fold.
"I will work as an active member of BJP and ensure the defeat of BJD in the forthcoming by-election in Kandhamal," Ray said soon after joining the BJP.
Ray, who represented Kandhamal in the Lok Sabha after being elected in the 2009 polls as a BJD candidate, was suspended from the ruling outfit for anti-party activities and was accused of working against the BJD after being denied a party ticket for the 2014 LS elections.
With Ray joining the party, speculation was rife in political circles about the possibility of him being fielded as BJP candidate for the Kandhamal by-election.
In a related development, senior BJP leader Bijay Mohapatra was appointed the campaign committee chairman of the BJP for the by-election in its state executive meeting today, a party statement said.
