The 21-year-old is arriving from American MLS club Inter Miami, where he has been impressing.
The talented midfielder is set to sign on January 1st, 2025, and will go straight into the senior team.
"We're looking forward to working with Diego very soon," said Brighton's head coach Fabian Hurzeler.
"He has already made a real impression both at club and international level.
"Like all young players who come to us from abroad, he will need a period of adjustment to the Premier League, but I feel he can make a big contribution and I'm looking forward to working with him."
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