Nothing is guaranteed yet, according to the London Evening Standard, but the Cobham academy graduate would provide much-needed cover at left-back for Kieran Tierney, whose minutes continue to be carefully managed because of his history of injuries.
Emenalo would become the fourth new addition to Martin O'Neill's squad this summer and the club's first defensive signing, alongside the recent arrivals of winger Haissem Hassan from Real Oviedo and Germany Under-21 midfielder Mika Baur from Paderborn.
Emenalo, the son of former Chelsea director of football Michael Emenalo, has represented both England and the United States at youth level and is naturally viewed as a central midfielder, but he has spent much of the past 12 months being deployed as a defender and has grown into an accomplished left-back in the process.
He caught new manager Xabi Alonso's eye with a series of forward-thinking displays during Chelsea's pre-season tour of Australia and Asia, form strong enough to spark talk that he could stay and provide senior cover following Marc Cucurella's departure to Real Madrid.
That possibility always looked unlikely given Chelsea's parallel pursuit of Rayo Vallecano's Pep Chavarria, who completed an £18 million move to Stamford Bridge on Wednesday and is expected to take up the left-back role behind Cucurella's replacement.
With that position now settled, Chelsea appear to have concluded that first-team experience elsewhere offers a better path for Emenalo's development than a fringe role in west London.
Emenalo has yet to make a senior competitive appearance for Chelsea, and Celtic have emerged as firm favourites to secure his signature ahead of next week's Champions League play-off first leg against LASK, continuing a well-worn pattern of the Scottish champions bringing in loan left-backs, following previous temporary deals for Marcelo Saracchi, Jeffrey Schlupp and Alex Valle in recent seasons.
Celtic's move for Emenalo also comes amid wider squad turnover at Parkhead, with the club reluctant to lose right-back Alistair Johnston amid interest from Everton and expecting an improved offer from West Ham for midfielder Arne Engels in the coming days. O'Neill has stressed a preference for quality over quantity in his recruitment this summer, with a goalkeeper also understood to remain on the club's shopping list before the transfer window closes.