Chinese-owned app welcomes the ruling against “unconstitutional law” due to come into effect in January.
A US judge has blocked Montana’s ban on TikTok, saying it violated the free speech rights of users.
In May, Montana became the first US state to pass the ban which was scheduled to take effect on 1 January.
The short-video sharing app, which is owned by China’s ByteDance, sued Montana a week later.
US District Judge Donald Molloy agreed with TikTok, saying that it “violates the Constitution in more ways than one” and “oversteps state power”.
The law would have made it illegal for app stores to offer TikTok, and firms would have faced penalties of up to $10,000 (£7,097).
