The 25 year-old right-back, who can also play as a defensive midfielder, signed for Farsley in October last year after he had completed his rehabilitation from an ACL injury.
Assenso had been training with the Celts since pre-season before officially joining them.
He previously came through the youth ranks at Leeds United and went on to play for Scunthorpe United, Ossett Town, Hartlepool United, Belper Town and Scarborough Athletic.
Assenso could go straight into contention this weekend as the Lions welcome fellow play-off contenders Gainsborough Trinity to Nethermoor.
Photo credit: Farsley Celtic
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