The 26-year-old, who primarily plays at left-back and will provide competition for Ali Koiki, has agreed a two-year deal at Sixfields after he was released by Newport County last season.
"Ryan is a good age with over 250 senior games already under his belt and he has a lot of experience for a player in his mid twenties," said Brady. "Much of his football has been played in League One or at the top end of League Two and he comes to us ambitious to help us progress.
"He will come in to give us depth and competition in the left-back position where he will compete with Ali Koiki for the shirt or he can also play further forward on the left hand side.
"Our own scouting of Ryan, the reports we have on him and his background and character are all positive and I am pleased we have been able to tie this signing up as he is someone who fits our template. He is a good size, he has a lot of pace and loves to get forward.
“He did have offers from League One and it is a credit to the club that we have been able to secure his signing. He is Northamptonshire born so he knows all about the club and our ambitions and we are delighted to have him on board."