Lazio condemned Reggina to relegation with a 1-0 win at the Stadio Olimpico.
Mauro Zarate's first-half strike was enough to end Reggina's six-year spell in Serie A.
The Argentine ace scored the only goal of the game on 26 minutes when he latched onto Ousmane Dabo's to poke the ball home.
Franco Brienza wasted Reggina's best chance to score on 37 minutes when he took the ball too wide in a one-on-one with Juan Pablo Carrizo to give the keeper and defence time to get back.
Brienza was denied by Carrizo in the second half as Lazio held on for the win to send Reggina down to Serie B.
The match was brought forward from the rest of Sunday's Serie A programme to give Uefa time to prepare the Stadio Olimpico for next week's Champions League final.