Twitter said it had detected an uptick in violations of terms of service by supporters of the theory, especially around "behavior that has the potential to lead to offline harm."
The most notable target was model Chrissy Teigen, who said she'd blocked innumerable accounts over harassment surrounding the theory.
Twitter says it will stop QAnon-related content from surfacing in searches, trends, and conversations, and will block links to QAnon related content, with the steps rolling out next week.
The move was first reported by NBC News.
QAnon metastasized out of the fringe "Pizzagate" conspiracy theory that emerged around the 2016 election, and first came to prominence when attendees of a 2018 rally for President Donald Trump in Tampa, Florida, appeared in Q paraphernalia.
Supporters fantasize, without evidence, that Trump is working in secret against a global Satanic pedophile ring, and have imagined for years the imminent arrest of dozens of celebrities and major Democratic figures.
The conspiracy theory has been associated with a number of real-life acts of violence, including a man who used an armored truck to block traffic on the Hoover Dam in 2018 and a man accused of fatally shooting mob boss Francesco 'Franky Boy' Cali last year.
QAnon groups were de-platformed from Reddit in September of 2018, and in May of this year Facebook took action against several pages tied to the movement.
However, more and more figures have been publicly espousing the theory, including a handful of Republican congressional nominees, while former National Security Adviser Mike Flynn recently tweeted a video of himself reciting Q-related oath.