Mr Shukla e-mailed his resignation this afternoon to Uddhav Thackeray.
Prem Shukla, executive editor of Shiv Sena's Hindi mouthpiece 'Dopahar ka Saamna', today resigned from his post.
Mr Shukla is likely to join the BJP, a source close to him said.
He was believed to have fallen out with Sena president Uddhav Thackeray of late.
Mr Shukla e-mailed his resignation this afternoon to Mr Thackeray, the Editor and Chief Trustee of 'Prabodhan Prakashan', the publisher of the tabloid.
Mr Shukla, who started his career with 'Nirbhay Pathik', joined 'Dophar ka Saamna' as chief reporter in 1993 before quitting in 1998. He was appointed as Editor by Uddhav in 2005, after his predecessor Sanjay Nirupam quit.
"Shukla had a few rounds of discussion with BJP's national general secretary (Organisation) Ram Lal followed by party president Amit Shah, which has paved his way to join the BJP," according to the source.
Mr Shukla was the party's face for putting forth its view on various issues before print as well as electronic media.
He of late stopped participating in television debates, reportedly at the behest of Mr Thackeray as the latter believed that Mr Shukla was siding with the BJP.
However, the source denied this contention. BJP and Shiv Sena share power both at the Centre and state government.