The company confirmed the changes, initially rumoured last week, explaining that the updated timeline meant it would now be easier for users to catch up with important tweets they might have missed.
The changes will be "initially opt-in", a spokeswoman told Marketing, but will be turned on via a notification in the longer term. Should they wish to, users can switch off the new timeline in iOS, Android or web settings.
Currently, when a user logs into Twitter, they generally see the most up-to-date tweets from those they follow, meaning anything posted overnight will be missed.
Now Twitter will analyse what kind of tweets users engage with to decide which content to show them, or "surface", when they log in. The number of "surfaced" tweets will depend on how long the user has been away, and how many people they follow.
That doesn’t mean Twitter will be dispensing with the chronological timeline. The firm said in an explanatory post: "Upon opening Twitter, the tweets [users] are most likely to care about from the accounts they follow will appear at the top of the timeline.
"The rest of the tweets will then be displayed directly underneath in reverse chronological order, like always."
Although Twitter’s most vocal users (primarily journalists) expressed outrage at the rumoured changes last week, tagging complaints with #RIPTwitter, Twitter was already behaving in a broadly similar way.
When users log in via Twitter’s apps or on desktop, the service often displays tweets that were posted "while you were away", usually floating content that it deems most interesting.
What it means for brands
Twitter claims the latest changes mean organic content from brands has a better chance of getting 'top billing', provided the content is interesting and relevant.
It also says the reshuffled timeline will keep users more engaged, meaning brands who do post good content will receive more clicks, likes and retweets than usual.
In theory, the updated timeline means that a British user interested in, for example, an overnight event such as the Super Bowl could wake up the next morning and see content posted by Super Bowl advertisers that they would have otherwise missed.
Promoted tweets and promoted accounts will not be affected by the change, according to Twitter, and brands will still be able to access the same measurement and targeting tools.
The news comes shortly after Twitter unveiled ‘First View’, which allows brands to place their video in the top ad slot on Twitter’s timeline.