"Starting today, you'll have more room to unleash your creativity on Twitter," said product development chief Jeremy Rishel in a blog post.
"Where previously, uploaded videos were limited to 30 seconds, now anyone can create video Tweets up to -- you guessed it -- 140 seconds long."
The new limit applies to video embedded in tweets.
Twitter also will be gradually easing the limit for its separate Vine app, known for its six-second "looping" videos.
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Twitter has been struggling to boost its user base, which has been stuck at around 300 million over the past few quarters, unable to expand past a core that includes politicians, celebrities and journalists.
Analysts say Twitter's format limiting tweets to 140 characters makes it harder to win mass appeal, and it has been overtaken by more visual services such as Facebook-owned Instagram, which announced today it now has 500 million users.
Rishel said there is growth in the use of video-embedded tweets that use Vine.
"And we love watching all the timely, important, and Twitter also allows some publishing partners to post videos up to 10 minutes long through its professional tools, which will remain unchanged.
Twitter announced yesterday it was acquiring British-based artificial intelligence startup Magic Pony to bolster its capacity for analysis of visual content.