About time, said Arvind Kejriwal, who founded the Aam Aadmi Party nearly two and a years ago and whose second bid for Chief Minister of Delhi could involve a direct duel with Ms Bedi.
"I always tried to convince her that she shud join politics. I am happy she did it today," Mr Kejriwal tweeted.
The BJP said it will decide on its chief ministerial candidate later, but Ms Bedi was not shy about serving up her credentials. "The last 40 years of my life have been dedicated to serving the public and the country," she said at a press conference seated next to BJP President Amit Shah and Finance Minister Arun Jaitley.
I have been fond of Kiran Bedi ji. I always tried to convince her that she shud join politics. I am happy she did it today.- Arvind Kejriwal (@ArvindKejriwal) January 15, 2015
Ms Bedi became the first Indian woman to join the Indian Police Service (IPS), won much praise for combatting the special treatment expected by and conferred on by Delhi politicians and VIPs, and introduced major prison reforms at the capital's high-security Tihar Jail.
Delhi votes for its next government on February 7; results will be counted three days later.
Ms Bedi, 65, and Mr Kejriwal, 46, were seen as the major programmers of the anti-corruption campaign that was fronted by Gandhian Anna Hazare in 2011.
The movement flourished in its early phase, rousing middle class India into demanding more accountability and stricter laws to punish the venality that drove a series of scams during the two terms of the coalition government led by the Congress. However, Mr Kejriwal was opposed in his decision to launch the Aam Aadmi Party by his mentor, Anna, and Ms Bedi.
In December 2013, Mr Kejriwal's political start-up turned out to the smash hit of the year, capturing a result strong enough in the Delhi election to form a minority government. 49 days later, in a move that he has publicly and repeatedly chided himself for, he resigned over the state legislature's refusal to clear the anti-graft legislation he had championed.