Pep Guardiola will return to Barcelona after Manchester City were drawn with the Spanish side in the Champions League.
The Spaniard, who won the European Cup as a Barca player in 1991/92, coached the Nou Camp side to the Champions League title in 2009 and 2011 before leaving for a three-year spell at Bayern Munich.
In addition, City will come up against Borussia Monchengladbach - who they defeated home and away last season - and Brendan Rodgers' Celtic, after beating Steaua Bucharest 6-0 on aggregate in the play-off round.
Leicester's first foray into the competition will see them play against Porto, Club Brugge and FC Copenhagen in the group phase.
The Premier League winners are taking part for the first time after their remarkable title success last season.
Elsewhere, Arsenal will come up against Paris Saint-Germain, FC Basel and Ludogorets as they participate in the Champions League for the 19th year in a row.
Tottenham are also in the tournament for the first time in five years and will be playing their home games at Wembley while White Hart Lane is redeveloped.
They will mark their return with games against CSKA Moscow, Bayern Leverkusen and Monaco. The first matches will be played on September 13 and 14, with groups running to early December.
Full draw
Group A: Paris-Saint Germain, Arsenal, FC Basel, Ludogorets
Group B: Benfica, Napoli, Dynamo Kiev, Besiktas
Group C: Barcelona, Manchester City, Borussia Monchengladbach, Celtic
Group D: Bayern Munich, Atletico Madrid, PSV Eindhoven, FC Rostov
Group E: CSKA Moscow, Bayer Leverkusen, Tottenham, Monaco
Group F: Real Madrid, Borussia Dortmund, Sporting Lisbon, Legia Warsaw
Group G: Leicester, Porto, Club Brugge, FC Copenhagen
Group H: Juventus, Sevilla, Lyon, Dynamo Zagreb