Brown, 18, has now been released by the Super League club and has agreed a contract at the Recreation Ground.
Salford are not running an Academy side this season so Brown, and others like him, were left without regular game time.
He featured in a couple of pre-season friendlies for Haven and did enough to convince coach Carl Forster that he was worth a contract when he was eventually released.
Brown learned his rugby through the age group teams at Seaton Rangers, from where he hails, and after his release by Salford, has continued to train with the Whitehaven squad.
The young forward had a year left on his contract with the Reds Devils at the start of the season.
“He’s a local lad who has obviously got something or he wouldn’t have been at Salford. He’s played at Under-19s for Salford, so League One would be the next step for him,” said Haven director James Robinson.
Coach Forster said: “I was approached by a pal at Salford to see if we would be interested in taking Lewis on loan.
"They wanted him to get some game time and, since he’s had a couple of games and trained with us, I think there’s something there we can work on.”
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