The 22-year-old joined from Latvian League side Skonto Riga and will initially join up with the club’s development squad.
Albion boss Gus Poyet told seagulls.co.uk, “He is a player we have been aware of for a while and we feel he has got the potential to bring more quality to our first-team in the future.
“He is a young defender who has quality on the ball. He will train with the development squad group under the guidance of Luke Williams to learn about the way we play here, then it’s up to him to earn his place in the first team.”
Maksimenko has already featured for Albion’s development squad side in a friendly against Barnet while on trial at the end of November and he is delighted to make the move to Brighton.
He added, “I am so happy to come to Brighton and to join this Championship team. The atmosphere at the club, the pitches and the stadium itself are all fantastic.
“I enjoyed the trial and waited for around four weeks to hear from the club, but when I did hear the good news I was so happy. They play good football here and don’t play the ball long so often, which suits me.
“When I was young I was always looking out for Latvian players in the Premier League and now I keep a close eye on Kaspars Gorkss at Reading because he’s the best defender in Latvia.
“I watched the game against Bristol City earlier this season and the stadium is amazing. I was watching the players, coaches, the fans and it’s all amazing. I am very excited at the challenge ahead.”