Pioli was sent packing after a dismal run which has seen Lazio win only two out of their last 10 league games, leaving them a modest eighth in Serie A. They have also been knocked out of the Europa League by Sparta Prague.
The club said Pioli would be replaced by former Italy international Simone Inzaghi, currently a youth team coach who spent most of his playing career at the club.
"Lazio announces that coach Stefano Pioli has been relieved of his position. The first team will be entrusted to Mr. Simone Inzaghi," the club announced in a brief statement.
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Unusually in Italy, it did not include a paragraph thanking Pioli for his work and wishing him luck in the future.
Pioli took over in July 2014 and led Lazio to a third-placed finish last season.
However, they began this season by losing to Bayer Leverkusen in the Champions League playoff round and have never seemed to have recovered.
Italian media said that several hundred angry Lazio fans gathered at the club's headquarters after Sunday's game and had to be dispersed by police.
(Writing by Brian Homewood in Berne, editing by Ian Chadband)
