Andrea Pirlo’s side began the day fifth but took advantage of Napoli’s 1-1 draw with Verona to finish fourth.
Juve cruised into a 3-0 half-time lead through goals by Federico Chiesa, Alvaro Morata and Adrien Rabiot.
Spaniard Morata scored his second shortly after the restart, before Riccardo Orsolini grabbed a late consolation for the hosts.
Elsewhere, AC Milan beat Atalanta – who had already sealed a top-four finish – to finish above their opponents in second place and book their Champions League spot.
Juventus, Italian champions for the past nine years, faced the prospect of a first season without Champions League football since 2011-12.
They never looked at risk of dropping points after Chiesa’s sixth-minute opener – which arrived after Rabiot’s shot rebounded off the crossbar – and Morata’s header from Paulo Dybala’s pass after 29 minutes put the visitors in control.
Rabiot added a third before half-time with a low finish from Dejan Kulusevski’s pass to effectively end the contest, before Morata produced a sublime touch before slotting in to make it 4-0 in the second half.
After Amir Rrahmani’s 60th-minute strike for Napoli, Davide Faraoni equalized for Verona to send Gennaro Gattuso’s side into the Europa League.
Franck Kessie scored a penalty at the end of both the first and second half to seal victory for AC Milan, who had not competed in the Champions League since 2013-14.
They finish 12 points behind champions Inter Milan, who celebrated their Serie A title with a 5-1 win over Udinese.