According to NFL Network's Ian Rapoport, the entry-level deal is worth $12.1 million, including a $6.8 million signing bonus.
The Packers entered the draft with a pressing need for physical, aggressive cornerbacks, and Alexander fit the bill at No. 18 overall following a series of trades.
In three seasons with the Louisville Cardinals, Alexander logged seven interceptions, 15 pass breakups and 77 total tackles despite being a tad undersized at 5'10".
"He's scrappy, he's competitive," Packers director of college scouting Jon-Eric Sullivan said, according to Jason Wilde of the Journal Times. "Is he as tall as some others? No, he's not. But I think when you watch the tape, he doesn't play like a little guy. He's very competitive, he gets in people's business.
"He's got a confident air about him, which is a good thing for any player—but a very good thing for a corner. He's an impressive kid. There's nothing, when you meet the kid, that would hold you back."
Now locked in as a long-term piece in Green Bay, Alexander projects as an immediate contributor in nickel packages who should help the Packers secondary make strides a year after it ranked 23rd against the pass.