Vale of Glamorgan Council will no longer use X (formerly Twitter) as part of its social media presence.
Council leader Lis Burnett said the platform, which was taken over by Elon Musk in 2022, had become "synonymous with abuse, misinformation and extreme views".
A spokesperson said there had been a "significant decline" in the platform's reach over the last two years.
The decision has been criticised by one Welsh Conservative councillor as "odd".
The council began tweeting in May 2009 and its peak, its account had 29,000 followers - but this has since dropped to 21,800 followers as of April 2025.
According to the local authority, increasing numbers of inactive accounts, along with changes to the algorithm driving content in users' feeds, has seen the number of impressions slump to less than 10% of those achieved two years ago.
The council made its last post on Thursday morning and will continue to use other platforms such as Facebook, Instagram and LinkedIn.
Cllr Burnett said: "This is a decision about values...we have set out our ambition of making the Vale a County of Sanctuary. One that is not only welcoming but that actively challenges discrimination and negative perceptions."
"As a council, we strongly believe that ensuring equality of opportunity is something that we should seek to provide for all citizens."
"With these ambitions in mind, X no longer feels like a space where we should be interacting with our residents. I recognise that many people still use the platform but it is simply not the right place to ask our community to engage with us."
"This is also a decision about making the best use of our resources. Recent changes to X have made it harder to engage with local people about our work."
"We will continue to engage with residents on other social media platforms, including Facebook, Instagram and LinkedIn."
Neighbouring local authorities in Cardiff and Bridgend are continuing to use X.
Cllr Rhys Thomas, Conservative councillor in the Plymouth ward of Penarth, said: "This is an odd decision, and yet another example of the Labour-run council trying to avoid scrutiny."
"Many Vale residents use X as a source of information, and it's vital that the Council has active accounts on social media platforms like X."
"Instead of indulging in their usual virtue-signalling, the council should take responsibility and focus on what matters to people across the Vale of Glamorgan."
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