The president later said Ukraine may have to hold an early parliamentary election if the crisis in the chamber persisted.
Parliament's website said that Mykola Tomenko, a deputy speaker, had also stepped down. Tomenko belongs to jailed opposition leader Yulia Tymoshenko's BYuT parliamentary faction.
The bill, which will not become law until first Mr Lytvyn and then Mr Yanukovich have signed it, would recognise Russian as a "regional" language in predominantly Russian-speaking ares, enabling its use in the public service.
Opponents of the bill say it was pushed through by Mr Yanukovich's party in order to win back disenchanted voters in its Russian-speaking power base ahead of a parliamentary election in October.
But opposition parties and millions who speak Ukrainian as their first language see the bill as a potential threat to Ukrainian sovereignty and its 20 years of independence since the break-up of the Soviet Union.
"This bill would push the Ukrainian language out of use," said one of the protesters, 40-year-old entrepreneur Yuri Chernyak. "It might be too late but we must do something and not stay indifferent."
More protests were planned across the country, opposition party Batkivshchyna said, and many protesters stayed out on the streets of central Kiev overnight.
People in large swathes of Ukraine, notably the eastern industrial heartland, speak Russian as their mother tongue.
Source: Reuters
