The 24-year-old confirmed it was an easy decision as the club mirrors his aspirations to reach the top tier of English football.
He told seagulls.co.uk, “Every player wants to play at the top level and I believe Brighton have got everything in place to get there.
"My decision to come here was to get to the Premier League and hopefully I can do that with Albion.
“I know Nathan Jones well and have spoken to him on the phone a couple of times, but he didn’t really need to sell the club to me as I have been here as a Charlton player and it is clear to see this is a big club, with a big ambition.
“The club are sitting in eighth position and it is a good place to be in at this stage of the season, so hopefully I can come in and help push the team on.
“I am delighted to have signed for such a big club, happy to have it done and dusted and happy to be here.”
Stephens being interviewed by Seagulls Player
The Bolton-born midfielder also highlighted Albion’s passing style as another factor in his move - and he has come up against Albion during his time at Oldham, Southampton and Charlton.
He added, “I know Oscar likes to play good football and with Nathan’s influence it is really appealing to me and one of the major reasons I came to this club.
“Albion have always been a difficult side to come up against and they have always played the best football in any division they have been in.
“I like to get forward and score a few goals but I know I have got responsibilities on the defensive side of things.
“I try to get involved with everything I can but if the manager has a certain role he wants me to play then I will obviously do that, so now my first port of call is meeting the lads and getting in the side.”
Albion v Doncaster at the Amex on February 8th, 3pm kick off. Tickets available online, at the Amex Ticket Office or via the telephone on 08443271901.