Former Arkansas resident Andrew Auernheimer was convicted in November of identity theft and conspiracy to gain unauthorized access to computers. Auernheimer's attorney had sought probation.
Auernheimer castigated the government for an unfair prosecution before a federal judge in Newark, N.J., pronounced his 41-month sentence Monday.
Prosecutors say Auernheimer was part of a group that tricked AT&T's website into divulging the email addresses, including those of New York Mayor Michael Bloomberg, film mogul Harvey Weinstein and other celebrities.
The group shared the addresses with the website Gawker, which published them in redacted form.
A second defendant has pleaded guilty.