The 20-year-old could make his debut at former club Preston on Saturday.
Monakana made 49 appearances for the Lilywhites before joining Brighton in January, although he has yet to appear in the Seagulls' first team.
Town boss John Gregory told the club website: "Jeffrey is highly rated by Brighton and he has plenty of experience of League One already.
"He's strong, quick and can deliver a good ball from wide areas and I'm really hoping he can flourish with us over the next month.
"With eight games during that time he will certainly get the opportunity to impress."
Monakana is Crawley's second signing on loan deadline day after Swansea winger Gwion Edwards also arrived on a month-long loan deal.