Chaudhary, sworn in the chamber of Speaker Brij Bihari Lal Butail, has been booked for murder by Haryana Police.
He was brought to Shimla, where a large number of his supporters were assembled, from Ambala jail under heavy security cover.
He is one of four suspects in the murder of a 24-year-old woman in Panchkula in Haryana Nov 22.
"It's a political conspiracy by my political rivals. I am innocent," Chaudhary told reporters after taking oath.
Asked about his confession, he said: "It's a police theory. I have full faith in the judiciary. I have never confessed that I committed the crime."
Ruling out the possibility of quitting the house in the wake of the J.S. Verma Committee report that legislators involved in woman-related crime should morally resign, he said he would come out clean.
"I will continue to work as a legislator. Even people are contesting elections from behind the bars," he said. "I have just submitted a list of his priorities as a legislator to the speaker."
After evading arrest, Chaudhary surrendered before a Panchkula court Jan 8, the day other legislators took oath.
Chaudhary is a first-time legislator from Doon in Solan district. He is the son of four-time Congress legislator Lajja Ram.
Shimla: Congress legislator Ram Kumar Chaudhary, who faces murder charges, Thursday took oath in the Himachal Pradesh Assembly after being brought from a jail in Haryana.
First Published: Thursday, January 24, 2013, 15:52