Blackburn
Armstrong, who made his Newcastle debut in 2014 at the age of 17 to become the club's second youngest Premier League player, has signed a four-year contract with Blackburn that promises to keep him in Lancashire until the summer of 2022.
Back.#ArmaReturns pic.twitter.com/xWMK7YZEa0
— Blackburn Rovers (@Rovers) August 6, 2018
The deal is believed to be worth an initial £1.75m rising to £3m.
After previously being handed the number 18 shirt during his loan spell, he will don the number seven shirt for Blackburn this season last worn by Liam Feeney.
In returning to Blackburn, Armstrong will link up once more with manager Tony Mowbray having enjoyed a very strong loan spell at Coventry City in League One under the boss earlier in his career.
To date, Armstrong has also spent time in the Championship on loan with Barnsley and Bolton.
A statement from Newcastle has wished the player well for the future.
Source: 90min