The sell-off is the first since JP revealed in January that it was exploring possible asset sales to help fund investment and pay down net debt.
The sale follows what has been described by JP as a “competitive tender process”.
JP chief executive Ashley Highfield said: “This disposal is further progress in executing our divestment strategy and allows the group to realise immediate value from our Isle of Man assets.
“I would like to thank the staff of our Isle of Man business for their loyalty and dedication over the years and we wish them well for a successful future.”
In January, JP said titles which could be sold off include those that are outside of selected markets, do not match its “audience focus” or do not offer the desired levels of digital growth.
Its Isle of Man portfolio had all been categorised as ‘core’ titles in a list sent to staff at the same time.
Newspapers listed in this group were described as making “a significant contribution and are important brands which sit right at the heart of Johnston Press”.
Isle of Man Newspapers Limited recorded a profit before tax of £598,000 (£632,000 before exceptional items) for the year ended 31 December 2015 and had gross assets of £1.78m at that date.
Tindle Newspapers chairman Sir Ray Tindle said: “Buying a profitable local weekly set-up such as the Isle of Man trio is certainly a departure from our early days when, without much cash, we mostly bought papers that were in trouble, or we had to launch them ourselves.
“We are most grateful to Ashley Highfield and his colleagues for all their assistance in bringing about this agreement.”
“We are unable to meet the whole of the staff until completion of the agreement takes place but I have asked Ashley and his colleagues Jason and Trudi and Warren kindly to convey to everyone that vice chairman Wendy Craig and I, and everyone at Tindle Newspapers, will make them all very welcome just as soon as we are able to do so.”