Jackson, 29, spent the last three seasons in Jacksonville racking up 18.0 sacks from the inside.
Jackson is set to earn $10 million in 2019, and none of it is guaranteed going into the final year of his contract.
Last month, new Bucs coach Bruce Arians had a long sit-down with Jackson, a conversation Arians said at the National Football League scouting combine "couldn't have gone better".
The 32-year-old Jackson was dumped by the Eagles after posting what still stand as career highs in receptions (82), yards (1,332) and TD catches (nine) in the 2013 season.
Jackson will receive a three-year contract worth $30 million, ESPN's Adam Schefter clarified, citing a source.
The team was reportedly seeking a potential trade partner for Jackson, whose preferred destination was his former team, the Philadelphia Eagles. He played just 79 percent of the offensive snaps last season and missed more than half the 2017 season, including the entire postseason, after wrecking a knee. He signed a big free-agent deal with the Jaguars entering the 2016 season and was very productive for.
Malik Jackson nearly certainly won't be the only top-of-the-roster player added in free agency.