The 21-year-old midfielder completed the move in time to be available to face Birmingham City on Saturday.
Brighton boss and ex-Liverpool player Sami Hyypia said: "The reports I have seen are very positive and my former colleagues at Liverpool have told me he is a very bright young prospect.
"We still plan to further strengthen the squad ahead of the deadline."
Teixeira joined Liverpool from Sporting Lisbon in 2012.
He had a brief spell on loan at Brentford last season before making his Liverpool debut in a 3-2 win at Fulham in February.
"Joao is an attacking player who likes to be on the ball and do his best work in the final third of the pitch," added Hyypia.
"I hope he will bring that extra edge to the team and our play and give us an extra dimension."
Meanwhile, Hyypia has said that Will Buckley made it clear he wanted to leave the club before his recent move to Sunderland.
The 24-year-old has been a key player for Albion in recent seasons.
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But Hyypia told BBC Sussex: "When someone doesn't want to play for you it's better that they move on."
The club also appear to have missed out on Stephen Ward, who ended last season on loan with them, but is expected to join promoted Burnley from Wolves.
"Before I came I heard about players here - and Will Buckley was one of the best-rated players," said Hyypia.
"I don't know what was wrong with him all pre-season, but he didn't really show why everybody was raving about him.
"I don't know if he knew that something was going to happen. I don't think I'm the only one who saw he wasn't the same.
"I would have liked to have had Will Buckley in top form. That wasn't to be."
With striker Leonardo Ulloa having been sold to Leicester, Buckley's departure was another blow for Albion fans.
And the club's hopes of signing Republic of Ireland international Ward, 28, on a permanent deal appear to have been scuppered.
"It's disappointing, but that can happen in football," said Hyypia.
"Worse things have happened and if Stephen Ward wants to play in the Premier League and doesn't want to come here, it's ok."
Brighton have signed Portugal Under-21 international Joao Carlos Teixeira on a season-long loan from Liverpool.