West Ham will play Dinamo Zagreb, Genk and Rapid Vienna in Group H.
Scottish champions Rangers have been drawn against Lyon, Sparta Prague and Brondby in Group A, while Celtic are in Group G with Bayer Leverkusen, Real Betis and Ferencvaros.
In the the Europa Conference League, Tottenham will play Rennes, Vitesse and NS Mura of Slovenia in Group G.
The first group stage matches will take place on Thursday, 16 September, while the final round of fixtures are due to be completed on 9 December.
This year's Europa League final will take place in the Ramon Sanchez Pizjuan in Seville on Wednesday, 18 May. The inaugural Europa Conference League final will take place at the Air Albania Stadium in Tirana on Wednesday, 25 May.
Leicester finished fifth last season to qualify for the Europa League for the second successive year, while West Ham secured a top-six finish to secure their place in the group stage for the first time.
The Foxes reached the last 32 of the Europa League last season before losing 2-0 on aggregate to Slavia Prague, who eliminated Rangers in the next round.
Steven Gerrard's side were beaten by Malmo in the Champions League third qualifying round earlier this month to drop into the Europa League qualifying play-off, where they edged past Armenian side Alashkert to clinch a group stage place in European football's second tier event for the fourth consecutive season.
Celtic have also reached the group stage for the fourth year in a row after surviving a second-leg scare to beat AZ Alkmaar 3-2 on aggregate.
Tottenham overturned a first-leg deficit against Pacos de Ferreira to reach the group stage of Uefa's new third-tier European competition after finishing seventh in the Premier League last season.
Before the draws were made, Villarreal forward Gerard Moreno was voted Europa League Player of the Season 2020-21 ahead of Manchester United duo Bruno Fernandes and Edinson Cavani.
Europa League draw in full
Group A: Lyon, Rangers, Sparta Prague, Brondby
Group B: Monaco, PSV Eindhoven, Real Sociedad, Sturm Graz
Group C: Napoli, Leicester, Spartak Moscow, Legia Warsaw
Group D: Olympiakos, Eintracht Frankfurt, Fenerbahce, Royal Antwerp
Group E: Lazio, Lokomotiv Moscow, Marseille, Galatasaray.
Group F: Braga, Red Star Belgrade, Ludogorets, Midtjylland
Group G: Bayer Leverkusen, Celtic, Real Betis, Ferencvaros
Group H: Dinamo Zagreb, Genk, West Ham, Rapid Vienna
Europa Conference League draw in full
Group A: LASK, Maccabi Tel-Aviv, Alashkert, HJK Helsinki
Group B: Gent, Partizan, Flora Tallinn, Anorthosis Famagusta
Group C: Roma, Zorya Luhansk, CSKA Sofia, Bodo/Glimt
Group D: AZ Alkmaar, CFR Cluj, Jablonec, Randers
Group E: Slavia Prague, Feyenoord, Union Berlin, Maccabi Haifa
Group F: FC Copenhagen, PAOK, Slovan Bratislava, Lincoln Red Imps
Group G: Tottenham, Rennes, Vitesse, NS Mura
Group H: Basel, Qarabag, Kairat Almaty, Omonoia