"I will join the BJP on September 1 in Solapur in the presence of BJP President Amit Shah who will address a rally," Rane, whose political journey spans the Sena and the Congress, told media persons here late on Thursday.
A Rajya Sabha Member elected with BJP support, Rane, 67, is likely to be accompanied by his politician-sons Nitesh and Nilesh.
He has also decided to merge his regional outfit, Maharashtra Swabhimani Party (MSP) - founded in October 2018 - with the BJP.
While Nitesh Rane is a sitting Congress MLA from Kankavali, Nilesh Rane is a former Congress MP from Ratnagiri-Sindhudurg Lok Sabha seat, with the Ranes a formidable force in the coastal south Konkan region, competing with the rival Shiv Sena.
Shah, BJP Working President J. P. Nadda, Chief Minister Devendra Fadnavis, state BJP chief Chandrakant Patil and other senior leaders will be present at the rally as part of Fadnavis' ongoing 'Mahajanadesh Yatra'.
Besides Rane, several high-profile stalwarts from the opposition Congress and Nationalist Congress Party are likely to be inducted into the BJP as the countdown for the state assembly elections commences.
Ruling ally Shiv Sena has already indicated its sour mood on the entry of Rane, its former member, to the BJP.
"It is akin to mixing salt with sweet milk," was the terse comment of senior Sena leader and Minister of State for Home Deepak Kesarkar to the development.
A shrewd politician who started at the grassroots level, Rane worked his way to become the Chief Minister in the Sena-BJP government in 1999 after the incumbent Manohar Joshi was removed by the party patriarch, the late Bal Thackeray.
After the Sena-BJP alliance lost power in 1999, Rane became the Leader of Opposition, but the warm relations turned cold with Thackeray expelling him for raising a banner of revolt against son Uddhav Thackeray (now the Sena chief).
Joining the Congress in 2005, he became a minister handling key portfolios under various Chief Ministers like the Vilasrao Deshmukh, Ashok Chavan and Prithviraj Chavan, but was constantly sidelined for the top post himself owing to intra-party power struggles.
He lost the Assembly elections in 2014 as well as a by-poll later and was made a Legislative Council Member in 2016, but the next year, quit the Congress for not keeping its promises of making him either Chief Minister or state party President.
A year later, Rane formed the MSP, which became part of the ruling National Democratic Alliance. He was given a Rajya Sabha seat in 2018, but the party did not contest the May 2019 Lok Sabha elections.
Rane has given hints of his future course in politics in his autobiography, "No Holds Barred: My Years In Politics", which was released in the presence of a galaxy of leaders.
( With inputs from IANS )