The company, which like many rivals has struggled financially amid declining print readerships and ad revenues, took the decision after a strategic review of its business which began last year.
The review took place ahead of a looming deadline for the repayment of £220m in loans.
The announcement of a sale was the only option it revealed in its statement to the market.
The company said: “Since commencing the strategic review of financing options first announced in March 2017, the company has focused on exploring all options available to it in relation to its £220m outstanding 8.625% senior secured notes due for repayment on 1 June 2019.
“Pursuant to this strategic review and in order to assess all strategic options to maximise value to its stakeholders, the board of Johnston Press announces today that it has decided to seek offers for the company.”
It added that there could be no certainty an offer would be made and it reserved the right to terminate the sale process at any time.
The company, which has about 200 titles, had hoped that a decision to buy the i national daily in 2016 would help revive its financial fortunes but it had remained loss-making to the extent it had been considering offloading other major titles, including The Scotsman, to raise cash.
It had blamed falling revenues more recently on changes to Google and Facebook algorithms which had hurt online exposure.
The company had a market value of £1.6bn in 2005 – a figure had since slumped to £3.4m ahead of the sale announcement.
The price had surged in August amid rumours of a mystery buyer for Johnston Press stock.
Bidders for the business could include activist shareholder Custos Group, which already owns more than 20% of the business and had said it would be a prospective bidder if the company collapsed.
Commenting on the statement Julie Palmer, partner at corporate recovery specialist Begbies Traynor, said: “We have all seen that there is a lot of stress in print newspaper with many of the regional newspapers across the UK culling staff and seeing news teams trimmed down to the bare bones.
“As such, this latest move by Johnston Press doesn’t come as a surprise. Even with the growing success of its flagship title, ‘i’, it still hasn’t garnered enough to be sure it will be able to pay the looming £220m of bonds next year.
“Like the retail high street that mirrors some of its issues, the move for media is online. Traditional newspapers have to find a way to adapt if they are to survive and thrive in this new world – and if they are to attract an investor the need for rapid evolution becomes even greater.”