The offensive tackle had been strongly linked to the Kansas City Chiefs, but was selected by the AFC South side with the second pick of the first round.
The 21-year-old told the team's website: "I'm really excited about getting down to Jacksonville, the weather is great, and that's always a good thing. I'm happy to be in Jacksonville. I'm happy to get down there. I understand now being the number two pick doesn't even matter.
"I'm a very detailed guy and I definitely want to be 100% comfortable by the time I get out there on the field on Sundays. I'm going to get that way because I'm a detailed guy and I'm not going to accept anything else than 100% comfortableness.
"I understand playing at right tackle. [Jaguars tackle] Eugene Monroe is a great player and I'm a guy that just wants to get on the field and wants to help my team. That's how I've always been. I've never not started a football game. I'm trying to get on the field and make my team better."
Joeckel won the Outland Trophy for best college interior lineman in 2012.