Jefferson, who turned 25 in January, entered free agency as one of the top defensive backs available, after having the best season of his career.
Since he signed with Arizona as an undrafted free agent in 2013, Jefferson has steadily improved each season. In 2016, motivated by receiving a low tender, Jefferson had 96 tackles while starting 14 games. The only noticeable blemish on his season was a sprained MCL suffered at the start of a Week 16 win.
He was the highest-rated Cardinals defensive back this season by Pro Football Focus, with a grade of 88.6. His run-defense grade of 98.0 was second overall, and his 7.8 run-stop percentage was the best among safeties, according to PFF.
In 63 career games, Jefferson has 276 tackles, five sacks, six forced fumbles, two interceptions (one for a touchdown) and two fumble recoveries.
Should the deal be finalized, it would mark the second straight offseason in which the Ravens have landed the top safety on the free-agent market.
Last season, Baltimore signed Eric Weddle, who was instrumental in recruiting Jefferson to Baltimore this offseason through social media.
The addition of Jefferson would likely mean the departure of Lardarius Webb, who has played eight seasons with the Ravens. Webb switched from cornerback to safety last season.
Baltimore can create $5.5 million in salary-cap space by cutting Webb.
ESPN's Josh Weinfuss and Jamison Hensley contributed to this report.