Italian newspaper Tuttosport have released a 24-man shortlist of candidates for the prestigious prize.
The best players on the planet under the age of 21 will battle it out to take the title, with the winner determined by a panel of 30 journalists.
Rashford finished as runner-up to Renato Sanches in 2016, with the now Swansea City loanee taking the prize on the back of his efforts in a successful European Championship campaign.
The United frontman is considered to be a serious challenger to the crown once again, but Mbappe is the strong favourite after bursting onto the scene at Monaco and earning a switch to PSG which will eventually cost them €180 million.
One man who has already completed a big-money switch is Barcelona winger Ousmane Dembele, although the Frenchman has picked up an untimely knock after moving to Camp Nou for €105m.
Other notable contenders include Manchester City striker Gabriel Jesus, who has impressed since arriving in English football in January.
Gianluigi Donnarumma remains a key figure at AC Milan despite being just 18 years of age, while Christian Pulisic and Kasper Dolberg are catching the eye at the highest level with Borussia Dortmund and Ajax respectively.
The nominees in full:
Gianluigi Donnarumma, Milan; Alban Lafont, Toulouse; Adrian Marin, Villarreal; Pol Lirola, Sassuolo; Malang Sarr, Nice; Matthijs de Ligt, Ajax; Dayot Upamecano, RB Leipzing; Theo Hernandez, Real Madrid; Amadou Diawara, Napoli; Federico Chiesa, Fiorentina; Youri Tielemans, Anderlecht; Benjamin Henrichs, Bayer Leverkusen; Ruben Neves, Porto; Kai Havertz, Bayer Leverkusen; Mikel Oyarzabal, Real Sociedad; Javier Ontiiveros, Malaga; Tom Davies, Everton; Nicolo Barella, Cagliari; Marcus Rashford, Manchester United; Kasper Dolberg, Ajax; Ousmane Dembele, Barcelona; Christian Pulisic, Borussia Dortmund; Gabriel Jesus, Manchester City; Kylian Mbappe, Paris Saint-Germain.
The winner of the 2017 award will be announced in October.
Whoever takes the title will add their name to a roll of honour which already includes the likes of Wayne Rooney, Lionel Messi, Sergio Aguero, Mario Balotelli, Paul Pogba and Anthony Martial.