"We do not have plans to develop a successor Reader model at this time," the Japanese firm told the BBC.
The PRS-T3 was the last version made and will exist as long as supplies remain in Europe.
Earlier this year, Sony pulled out of selling e-books and directed its users in the US and Europe to the e-bookstore of rival Kobo.
North American customers using Sony Readers have been directed to buy books from Kobo since February this year, and European and Australian customers since May, a Sony spokeswoman said.
But users in Japan, Sony's home country, can continue to still get its line of Readers and access Sony's Reader Store.
The news was first reported by German site Lesen.
The dominance of Amazon's range of Kindles and the growing smartphone, tablet and so-called phablet market have made it hard for Sony's suite of e-readers and rivals like Nook to carve out a niche for themselves. According to The Bookseller, Amazon has around 90% of the dedicated e-reader market in the UK.
Canadian firm Kobo was bought by Japanese e-commerce company Rakuten, which is looking to grow its business globally in a bid to challenge Amazon.
The global market in dedicated e-readers peaked in 2011 with 23 million devices sold, but is expected to fall to 10 million by 2017 as phones and tablets eat into the overall market, according to the research consultancy Gartner.
Still, the sale of printed books will be outstripped by e-books by 2018, a report by Pricewaterhouse Coopers suggested.

It is looking to raise more than $900m (Â£624m) from investors, which would value the firm at more than $5bn.
The listing, planned for July, could make it the world's biggest technology initial public offering this year.
Line is looking to raise funds to expand into the US and help it compete with rivals such as Facebook Messenger, WhatsApp and China's WeChat.
The app first made its debut in 2011 and is the most popular messaging service in Japan, Thailand and Taiwan.
It is famous for selling animated stickers and stamps that people can share while chatting. Line also provides free voice calls and services such as music streaming.
Line's management have looked to take the company public for several years now. It submitted an IPO application to the Tokyo Stock Exchange in 2014.
However, those plans were shelved at the time due to weak global markets.
Line had 218 million monthly active users at the end of March.

The hardware retailer's fourth quarter sales rose 9.5% to almost $21bn (Â£14.9bn) between November and January compared with the same period in the previous year.
The company has benefited from pent-up demand in the housing market.
On Tuesday the National Association of Realtors reported existing home sales rose by 0.4% in January - on top of a 12% surge in sales in December.
Low interest rates, combined with growth in the job market and wage increases, have bolstered the US housing market, but fears of slowing global growth could dampen confidence this year.
Home Depot sales were also helped by unusually warm winter that has allowed more people to continue home improvement projects throughout the winter.
Like-for-like sales rose 8.9% - far higher than analysts' estimates of 5.3% growth.
The higher sales resulted in Home Depot posting a profit of $1.47bn for the fourth quarter, higher than the $1.37bn for the same period in 2014/15.
Shares of Home Depot rose 2% in afternoon trading in New York.
The company also announced it would increase its quarterly dividend by 17% and conduct a $5bn share buyback this year.
Despite the recent gains, the outlook for the US housing market in 2016 remained uncertain.
The National Association of Realtors said that housing inventory fell by 2.2% from last year, leading to higher prices. The median existing home price was $213,800 across the US, up 8.2% from January 2015.
"The spring buying season is right around the corner and current supply levels aren't even close to what's needed to accommodate the subsequent growth in housing demand," said Lawrence Yun, the association's chief economist.
"Home prices ascending near or above double-digit appreciation aren't healthy - especially considering the fact that household income and wages are barely rising," he added.
Sony has given up selling its line of Reader devices for e-books after failing to find a big enough market.
[NEXT_CONCEPT]
Japanese phone messaging app operator, Line, has said it plans to list its shares in both Tokyo and New York.
[NEXT_CONCEPT]
Home Depot has reported better than expected sales growth, helped by a strong US housing market.