A Russian court found Marina Ovsyannikova guilty of flouting protest legislation when she interrupted a live news bulletin on state TV and denounced the war in Ukraine, the RIA news agency reported. She was fined 30,000 roubles (£210).
Ms Ovsyannikova, a Channel One employee, held up a sign behind a studio presenter reading the news on Channel One on Monday night and shouted slogans condemning Russia's invasion of Ukraine.
In her first interview following her sentencing, the television editor told the media that she had endured one of the hardest days of her life, and needed to rest before giving more comments.
“I want to thank everyone for their support, friends and colleagues...It’s been a really difficult day in my life. I’ve gone two days without sleep, more than 14 hours in custody, they didn’t allow me to contact those close to me or to receive any legal counsel... so I found myself in a really tough situation.
“It was my anti-war decision. I made this decision by myself because I don’t like Russia starting this invasion. It was really terrible,” she told the BBC as she left the courthouse.
Her bravery has been heralded around the world, with Foreign Office minister James Cleverly on Tuesday saying the stunt was “really important” in telling the truth about the conflict.
The Prime Minister's official spokesman paid tribute to her bravery on Tuesday saying: "The PM wants to pay tribute to all of those in Russia standing up to Putin's campaign of violence.
"It is an illustration that there is a significant proportion of the people of Russia who do not believe this war is in their name and are incredibly bravely standing up to make that clear."
Lawyers were unable to locate Ms Ovsyannikova for several hours after she was detained on Monday evening.
Her whereabouts were unknown until an image circulated on Russian media showing Ms Ovsyannikova in court with lawyer Anton Gashinsky.
Earlier reports claimed Ms Ovsyannikova appeared at a Moscow court on Tuesday charged with "organising an unauthorised public event".
That would amount to a less serious offence than the new censorship law passed earlier this month by Mr Putin, which criminalises the spread of information that is considered by the Kremlin to be "fake" news, controlling what can be reported about the conflict with Ukraine.
Ukrainian President Volodymyr Zelensky also praised Ms Ovsyannikova's actions.
Russian state TV regularly amplifies the Kremlin’s line that troops have entered Ukraine on a “special military operation” to save the country from “neo-Nazis”.
Any suggestion of a war being waged against Kyiv branded as disinformation by the Kremlin, including a ban on the word “war” being used by media outlets.
Moscow has also blocked social media sites like Twitter and Facebook.