Dharun Ravi, 20, reported to the Middlesex County jail on May 31, though he could have remained free while his case is appealed.
A judge sentenced him to 30 days in jail -- far less than the 10-year prison sentence he could have given him. He still faces three years of probation, plus more than $11,000 in fines and assessments, 300 hours of community service, and counseling.
Like other county jail inmates, Ravi automatically was given five days off for good behavior and five for working. Jail officials say he has not done anything to have those credits taken away.
Federal immigration authorities said Monday that Ravi will not be deported to his native India. He lived there until he was 5 years old and remains a citizen, though he is in the United States legally.
Foreign citizens convicted of crimes here can face deportation -- usually after they complete their prison or jail terms. Last year, Ravi rejected a plea deal under which prosecutors would have sought to protect him from being deported.
Ravi's supporters argued for leniency in part to make it less likely that he would be deported. Experts say the proceedings are usually initiated against those who are incarcerated for a year or more.
Ravi was convicted in March of 15 criminal charges, including bias intimidation, invasion of privacy and tampering with a witness.
Jurors heard during a trial that lasted three weeks that he used a friend's computer in September 2010 to view a few seconds of live streaming video from his own dorm-room webcam and saw roommate Tyler Clementi and another man kissing.
He told others about it in person, in texts, instant messages and tweets -- and alerted others again two days later that Clementi, 18, wanted the room to himself again. That time, the camera did not operate.
A night later, Clementi committed suicide. His story has been held up since then as a prime example of what can go wrong when young gays are bullied, though Ravi was not charged with the death.
Prosecutors are appealing the sentence, arguing that Ravi should have to serve more time for his actions. Ravi is appealing the conviction, saying he is not guilty.
Ravi's lawyer has said he'll start paying off the fines and begin working on the community service part of his sentence.