Broadcasters must urgently adapt to an existential threat from “creator journalism” that is causing audiences to shun traditional television news, the former boss of BBC News has said.

Deborah Turness, who resigned from the BBC alongside the then director general, Tim Davie, last year, said consumption was “collapsing” for traditional television news, which was facing “a profound moment of disruption”.

She said that a new habit of following personality-led journalism on digital platforms such as YouTube, TikTok and Substack was now in the process of replacing traditional news. She said the impact of the shift may be “greater than the advent of the digital age, or the arrival of social media”.

In her first intervention since stepping down from the BBC after the corporation’s edit of a Donald Trump speech, Turness said traditional broadcasters had to quickly react to the “existential nature” of the revolution taking place.

Turness pointed to a major decline in TV news audiences, stating that nearly 4 million fewer people had been sourcing their news from TV in the past five years, including streaming. “At the same time, we’ve seen a trebling of the number getting their news from YouTube – a 10-fold increase from TikTok,” she said.

Giving the Sir David Nicholas memorial lecture in London, named after the pioneering former ITN editor, Turness said she had spent her time since leaving the BBC examining the new form of “one-to-one” journalism, which is delivered through digital platforms.

She said it went against “the polished, controlled formality that is in the DNA of the established media”.

She said that trust in individual figures was behind the shift away from broadcasters, pointing to the huge audiences already assembled by some creators. She singled out Joe Rogan, who has 20.9 million subscribers on YouTube; the former Fox News anchor Tucker Carlson, who has 5.6 million; his fellow rightwing commentator Megyn Kelly, with 4.2 million; and Mehdi Hasan, with 1.95 million.

“I believe that the established media hasn’t confronted the hard truth, that this revolution isn’t just about consumers moving to different platforms. It’s that they are choosing more direct forms of journalism,” she said.

“This creator journalism is not a side-show. It is fast becoming the show. If we have been wondering for years what would eventually replace the broadcast news mass media model, we are seeing the answer now.

“Will we wake up to the existential nature of this great shift in our industry? Will we respond with the speed, urgency and purpose required? Or will we be like the proverbial frog in boiling water, who knew it was getting warm, but failed to jump?”

While the trend is most developed in the US, major news broadcasters around the world are grappling with the same problem. Many are trying to create the same direct relationship between journalists and their audiences as content creators.

In the UK, Sky News has launched a strategy promoting its most prominent journalists, with podcasts and plans for exclusive footage and commentary from specialist journalists with the biggest followings.

Turness said this was the right approach, while acknowledging a tension between the opinionated world of many content creators and the traditional tenets of impartiality in broadcast television.

“What we are witnessing is the wholesale shift from one established information ecosystem to another,” she said. “And, if we’re honest, one where established news providers have so far struggled to authentically play at scale.

“My recent conversations have only strengthened my view that news providers are going to have to be more prepared to liberate their talent.”

She added: “The brutal truth is that, even with all this innovation, most large news organisations remain structured around broadcast – with key decisions being made with a broadcast-first approach. Yet I would argue that, if the established media are to thrive – or even survive – they need to start from where the consumer is.”