Days, who announced his decision during an online talk show appearance in Baton Rouge on Tuesday, had previously declared his intention to enter this summer's NBA draft after last season. However, he did not hire an agent or otherwise relinquish his college eligibility.
Days started 28 of LSU's 29 games last season, helping the Tigers advance to the SEC tournament final for the first time since 1993 and win a first-round NCAA tournament game. He averaged 11.6 points and a team-high 7.8 rebounds a game. He made 51.9% of his field goal attempts and shot 40% from 3-point range.
His eight double-doubles as a junior tied for the SEC lead last season and gave him 16 for his career.
"I love Louisiana. I love the people. It's going to be a fun ride," Days said on "The Jordy Culotta Show," adding that he looks forward to his "last ride" with coach Will Wade.
"I'm the last one left with all the guys I came in with and we're looking for a title. We're trying to win a title this year," Days said. "I heard about some of the games in practice over the summer so I'm very excited about the new guys and some of the returning guys. I'm excited about this season."
Days took more of an exploratory approach by maintaining his eligibility and now returns to a team welcoming several highly rated recruits including center Jerrell Colbert of Germantown, Tennessee, guard Brandon Murray of Baltimore and forward Alex Fudge of Jacksonville, Florida.
Days, who has played in 94 career games with 61 starts, is on pace to reach more than 1,000 career points, with 852 so far to go with 571 career rebounds. He also has 117 career 3-pointers.
He's scored as many as 24 points in a game against Southern Illinois-Edwardsville last Nov. 26, grabbed as many as 16 rebounds in a game on Jan. 8 against Arkansas and his as many as five 3-pointers against Vanderbilt on March 9, 2019.