Veteran striker Eto'o, 33, was paraded on the pitch by club president Massimo Ferrero alongside fellow new recruit Luis Muriel following the 1-1 draw with Palermo.
The Cameroonian had earlier taken his place in the stands to watch his new side, who were pegged back after Eder's sixth-minute opener.
Eto'o also posted a picture of himself wearing a Sampdoria training top on Twitter on Sunday morning, adding the message: "Successful medical. Thank you Dr Parfait Ondo. Ready for a new challenge!!!"
The four-time African Player of the Year only joined previous club Everton in August after his contract at Chelsea expired. He made 14 Premier League appearances this season, scoring three goals.
The move will herald a second spell in Serie A for Eto'o, who spent two years with Inter from 2009, during which time he scored 53 times in all competitions.
Everton duly posted a statement on their official website on Sunday, confirming Eto'o has undergone a medical and is set to officially complete his switch to Sampdoria on Monday.
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