In a hectic round of voting in the chamber, near where triumphant but wary protesters remain encamped on Kiev's main square, the president was stripped of his abandoned country home.
Its brash opulence has fuelled demands the Russian-backed, elected leader and his allies be held to account for corruption on a grand scale.
EU officials said they were ready to help Ukraine, while Russia, its strategy of funding Mr Yanukovich in tatters, said it would keep cash on hold until it sees who is in charge.
Parliament-appointed security officials announced legal moves against members of the ousted administration and those responsible for sniper fire and other police attacks on demonstrators in violence that left 82 dead in Kiev last week.
A day after dismissing Mr Yanukovich with the help of votes from his own party, parliament handed his powers temporarily to Oleksandr Turchinov, who was elected speaker on Saturday.
An ally of newly freed opposition leader Yulia Tymoshenko, Mr Turchinov called for an interim prime minister to be in place by Tuesday to run the country until a presidential election on May 25.
Among contenders may be Ms Tymoshenko, 53, who lost to Mr Yanukovich in 2010 and was then jailed for corruption. She ruled herself out of the post of Prime Minister yesterday but may still have her eye on the top job of president.
Mr Yanukovich, 63, denounced what he called a "coup d'etat" reminiscent of Nazi Germany. He spoke on television on Saturday from what looked like a hotel room in a city near the Russian border after a flight he tried to board to Russia was prevented from taking off.
With pro-EU protesters still controlling central Kiev, and crowds on the streets in other towns and cities, parliament is under pressure to demonstrate its authority across the nation and to calm fears of a split with pro-Russian regional leaders in the fallen president's eastern political base.
Vitaly Klitschko, a former world boxing champion and a leading figure in the uprising, said: "In these days the most important thing is to form a functioning government.
"Parliament is the last legal official institution in Ukraine. Nobody knows where the president is. We tried to find him all day yesterday. His location is unknown. He left the country without a president."
Even the president's Party of the Regions, backed by many of the wealthy "oligarchs" who dominate Ukraine's post-Soviet economy, seems to have given up on a wavering leader with whom Moscow had last week appeared to be losing patience.
Instability in Ukraine is a major concern for both Russia, where President Vladimir Putin supported the Yanukovich administration financially, and for the EU which had offered Ukraine a far-reaching trade pact Mr Yanukovich rejected in November.
It was that decision, taken after threats of retaliation from Moscow, which sparked the protests.
British Foreign Secretary William Hague warned Russia against undermining EU aid - a reference to its threats of trade sanctions last year - and against other intervention.
Russia docks its Black Sea fleet on Ukraine's Crimea peninsula - a region that, like Mr Yanukovich's home city of Donetsk and other industrial areas in the east, has many native Russian-speakers and strong cultural ties to Moscow.
Reflecting anger in Russia, where Mr Putin sees Ukraine as a key element in a future customs union, Foreign Minister Sergei Lavrov said: "Illegal extremist groups were refusing to disarm and in fact are taking Kiev under their control with the connivance of opposition leaders."
The acting prosecutor general told parliament an order had been given to arrest his predecessor.