Hazel Kelly scored a second-half goal for Roscommon but the Orchard County found another gear thereafter and ran out 1-20 to 1-10 winners at Clane.
Armagh led 0-11 to 1-4 at the break before Kelly found the net. Four successive scores saw Armagh retain their four-point advantage.
Niamh Fitzgerald was on target late in the half to try and break Armagh’s momentum. However this was in vain as points from Eimear O’Kane and Rachael Merry concluded the action.
Following the half-time break again it was end-to-end as the sides traded scores, but Ciara Geoghegan’s second half goal proved decisive.
Roscommon looked to take the edge off with a Kelly free. However, Armagh added a further trio of points and moved nine clear mid-way through the second half.
Despite responding with three of their own Roscommon were unable to complete a comeback as Geoghegan hit four in the final eight minutes.
Geoghegan could even afford to miss a penalty and still see her side win well.