The latest software modification at the one-to-many messaging service comes about a year after Twitter set out to relax a 140-character limit set due to mobile phone text messaging constraints in place when Twitter launched in 2006.
Twitter first announced plans to relax the limit a year ago, as part of an effort to bring in more members and make the platform easier to use.
"Remember how we told you we were working on ways to let you to express more with 140 characters?" Twitter product manager Sasank Reddy said in an online post.
Providing more room in tweets is seen as a way to encourage more use and sharing of pictures, videos and links.
The move is part of a push by Twitter to increase its user base and engagement, which have sputtered to the chagrin of investors.
"Our work isn't finished," Reddy said.
"We'll continue to think about how we can improve conversations and make Twitter easier to use."