Singh, who is the MP from Etah Constituency, has also resigned from the Lok Sabha. (Agencies)
"I have written a letter on February 25 resigning from the Lok Sabha and joining the BJP now," he told mediapersons.
Singh could not join BJP earlier owing to the fear of disqualification in Parliament as the outfit, Jankranti Party, he had formed after quitting BJP during the 2009 Lok Sabha elections, merged with the saffron outfit in January 2013.
At the time of merger, his party was headed by his son Rajbir Singh.
Singh said he did not join BJP earlier to avoid disqualification from the Lok Sabha.
The former Uttar Pradesh chief minister said he will join BJP as a common worker and would continue to work for it as common worker.
Singh, however, said that he has sought a nomination from the same constituency and would contest if given the ticket.
Lauding Modi’s leadership, Singh said the workers' inaction has come to an end under him.
“Modi's leadership and workers' action would help the BJP emerge victorious," he said.
"There is a Modi wave as of now which would turn into a storm till the voting day," Singh said
Terming Third Front as 'bhanumati ka pitara' (a group having too many leaders), Singh said the country is faced with many challenges and people have to decide whether they wanted a firm or an indecisive government.
Inflation and corruption are burning issues in these elections and the Congress-led government had been successful in increasing both during its tenure, he said.
Singh, who is the MP from Etah Constituency, has also resigned from the Lok Sabha.