According to the DP, Montgomery will get a one-year deal worth $1.325M, with playing time incentives available to boost that figure.
Montgomery is expected to compete with Manny Ramirez for the starting center job, with the loser potentially ending up in Zane Beadles' old spot at left guard.
As per the DP, the addition of Montgomery figures to put off any plans to move Orlando Franklin, who will apparently compete with Chris Clark to keep his right tackle job.
But Jeff Legwold says Franklin could still end up inside, depending upon how well the Broncos see Clark fitting on the right side.
The 31-year-old VA Tech alum was originally drafted by John Fox's Panthers in 2006, spent his second season with the Jets, and had been in Washington ever since.
A guard for his first four NFL seasons, Montgomery shifted over to center when former Denver draftee Kory Lichtensteiger was injured in 2011.
Washington cut the Maine native in March, with Lichtensteiger set to finally take his old job back from Montgomery.
In 1,172 snaps last year, the 6-3, 304-pound lineman graded out at +4.8 according to PFF.
He was good for a +21.8 grade in 1,112 snaps in 2012, and has missed just six snaps over the past three seasons - all during a single game in 2012.