The 24-year-old was available on a free having reached the end of his deal at Cardiff City this summer, and he returns to the Yellows where he spent the second half of last term on loan.
The Northern Ireland international is a very versatile left sided player and will offer plenty of tactical flexibility to Karl Robinson, in hoping to compete towards the top end of League One again.
Robinson explained what Brown will bring to the Kassam Stadium when he spoke to the club’s website.
He said: “He is a full international, an excellent defender who can play in a couple of positions, his long throw gives us an extra option and most of all he is a good player with a fantastic attitude who we believe is going to get better and better.
“He settled in well last season and we’re really pleased that he is back with us.”
The Yellows’ recruitment has been outstanding in recent years but it does seem like they are going to have to lean on it once again this summer, with key players moving on to higher places.
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Oxford have consistently sold their better players to higher divisions in the last few seasons and this summer appears to be no different.
The club have been able to tie Alex Gorrin and Elliott Moore down to new contracts, while Mark Sykes left for Bristol City on a free transfer.
Luke McNally could be on his way soon, which would leave a hole in the backline for Robinson to fill.
Oxford play a very attractive and attacking brand of football under Robinson, and that suits an intelligent player like Brown.
The Yellows sometimes play in the third tier during international breaks, which may decrease the appeal of a signing like Brown, but the 24-year-old should still be able to positively contribute to another promotion tilt next term.