Born in Freetown, Sierra Leone, on 12 December 1994, Nathaniel signed his first professional contract in January 2012 having turned 17, putting pen to a two-and-a-half year deal.
That was halfway through his first season full-time at the club, a campaign that saw him regularly captain the reserves and the FA Youth Cup side.
Nathaniel is used to playing above his age having made his England Under 17 debut aged 14. He became a European champion at that international level in the summer of 2010, playing in the same team as Josh McEachran, and he later captained that side as well.
Tall and able to play in central defence or midfield, he came through the Chelsea Academy and also played for England Under 16s.
Despite his tender age, he was a key figure in the reserve squad that won the national championship in 2011, and has now graduated to the national Under 19 group. He has been an unused sub for the first team.
He was captain of the side that won the 2012 FA Youth Cup and ended the season as part of the first team squad that flew to Munich for the Champions League Final.
On 31 August 2012 he joined Championship side Watford, managed by Gianfranco Zola, on loan. The loan initially stipulated that Chalobah would return to Stamford Bridge in January 2013. However, after impressing at Vicarage Road and featuring regularly, the deal was extended until the end of the season.
Chalobah played a pivotal role in a side pushing for promotion to the Premier League, scoring a stunning strike in a win at Leicester City in the penultimate league game. Eventually the Hornets finished third so entered the play-offs. Chalobah ended his spell at Watford by playing 73 minutes at Wembley but unfortunately Zola's side slipped to a 1-0 defeat against Crystal Palace after extra-time.
It was still a wonderful season for the youngster's development. He played 42 first team matches and was named the Football League's Young Player of the Month for April.
Having spent the 2013 summer tour of Asia with the first team where he played a part in all three matches and received praise from Jose Mourinho (who predicted a Chelsea future for the player after one more season on loan), on 19 September Chalobah moved on loan to the Championship again, this time with Nottingham Forest.
He spent the first half of the season in the East Midlands, playing 12 times and scoring one goal before moving to another Championship club in January, joining Chelsea team-mate Kenneth Omeruo on loan at Middlesbrough for the rest of the campaign.
Nathaniel is used to playing above his age having made his England Under-17 debut aged 14. He became a European champion at that international level in the summer of 2010, playing in the same team as Josh McEachran, and he later captained that side as well.
A captain of the Under-19s, he played his first Under-21 game against Northern Ireland back in November.
On 3 February, Chalobah was named England Men's Youth Player of the Year at an FA awards ceremony, a prize which recognised his contribution at both Under-21 and Under-19 level.
In June 2013 he played for England Under-21s in the European Championships in Israel.