Former PSV Eindhoven trainee Sanoh will officially join the Reds at the end of his contract on 1 July.
The Dutchman, 21, made 26 appearances last season, scoring five goals.
He is Crawley's first signing since the League Two club appointed former Liverpool and Leeds star Harry Kewell as head coach on 23 May.
Find all the latest football transfers on our dedicated page.

Charlie Craig, 15, from Derbyshire, was a rider at apprentice level with the GB Cycling Team's Rider Route.
The boy's father, Nick Craig, broke the news on Facebook saying the family's world had fallen apart, Cycling Weekly reported.
British Cycling's programmes director Andy Harrison said the organisation was "devastated by the news".
The teenager won the under-16 National Trophy Cyclocross Series in 2016 and was highly thought of in the cycling world.
Mr Craig, himself a national cyclocross champion, said on Facebook: "Our beautiful lovely little boy Charlie went to sleep but never woke up.
"I don't know what else to write just now, but he will be with his little angel niece."
Many people posted messages on Twitter, including Dame Sarah Storey, winner of 15 Paralympic gold medals, who tweeted: "Devastated to hear the news about Charlie Craig, what a tragic loss."
Mr Harrison, from British Cycling, said: "Charlie was a promising young rider who had his whole life ahead of him.
"Everyone involved with the team is devastated by this news and, naturally, all of our thoughts are with Charlie's family."
It is not known at this stage how he died.

Sylvia Bradshaw, of Fakenham, Norfolk, heard an appeal by Gamble Plant Skip Hire to find relatives of Gwendoline Harding, whose remains were found in a metal urn in one of its containers.
She had been cremated in March 1996 at West Hertfordshire crematorium.
Ms Bradshaw thanked the skip firm for being "decent human beings". "They've done a tremendous thing," she said.
She heard her relative's name on a BBC Radio Norfolk appeal, where skip firm office manager Alex Dunmore said it was doing all it could to trace the family.
He said the firm had contacted the people who ordered the skip but they did not recognise the name.
Ms Bradshaw said she was "at a complete loss" as to how the remains ended up in the skip.
She believed the urn had been with her father, Allan Bradshaw, in Little Snoring. Mr Bradshaw is no longer alive.
Her grandmother had lived in Elstree for many years and was living in a Harrow retirement home when she died, aged 83.
The ashes had been brought to her son - Mr Bradshaw - in Norfolk.
Ms Bradshaw now plans to take the urn to her aunt Julie Hall, her grandmother's eldest daughter. She once took the ashes on an Orient Express trip, as that had been her mother's lifelong ambition.
"I feel like she's has lots of journeys now, after this," Ms Bradshaw said.
"It'll be just nice that she'll be back with her family.
"It's an emotional day - I'm happy, tearful and sad at the same time."
Crawley have signed midfielder Moussa Sanoh on a two-year contract after he was not offered a new deal by Dutch second division side RKC Waalwijk.
[NEXT_CONCEPT]
Tributes have been paid to a "promising young cyclist" who died in his sleep on Friday.
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The granddaughter of a woman whose ashes were found in a skip said it was a "massive shock".