[4][2] In the early 1990s, Cowley began publishing reviews, literary essays and articles in British newspapers and magazines, including writing for The Bookseller from 1992 to 1995.
Under his editorship, the New Statesman's print circulation increased from 23,000 to 33,000 by 2015, traffic to the magazine's website reached a new record high in June 2016, with 27 million page views and four million unique users, and the magazine has become profitable.
In 2019, he edited and wrote the introduction to Statesmanship: The Best of the New Statesman (1913–2019), which was published in hardback by Weidenfeld & Nicolson.
The judges said that Cowley had transformed the New Statesman and "created issues of the magazine that were the envy of the industry".
The awards committee said: "Cowley has succeeded in revitalising the New Statesman and re-establishing its position as an influential political and cultural weekly.
[17] At the 2020 British Society of Magazine Editors (BSME) awards, Cowley was named Current Affairs and Politics editor of the year for the fourth time, defeating rivals from The Spectator, The Big Issue and Prospect.
"In increasingly tribal times, Jason Cowley continues to champion independence of thought and diversity of opinion, challenging his audience and producing a magazine that’s imaginative, unpredictable and interesting," the BSME judges said upon presenting the award.