Real Madrid legend Ramos, back in Spain with Sevilla after a two-year spell at Paris St-Germain, was playing a record 34th La Liga match against Barcelona.
And the 37-year-old settled the game when he shinned Lamine Yamal's header across goal and past his own keeper.
Barca deserved the win and Joao Felix smashed a shot off the underside of the crossbar in an open first half.
Barca lost Raphinha to a first-half hamstring injury in the one downside to a result which took them top of La Liga, above neighbours Girona.
Sevilla did not have not any representatives in the VIP box in protest at the corruption case surrounding Barcelona.
Barcelona face charges over payments made to Jose Maria Enriquez Negreira, a former vice-president of the referees' committee, in return for favourable refereeing decisions.
Uefa is also investigating the matter.
The Spanish Civil Guard searched the headquarters of the Spanish Technical Committee of Referees on Thursday.
A Sevilla statement read: "We express our complete outrage and condemnation of the actions carried out by the former officials of FC Barcelona who are indicted in the Negreira case, actions that are allegedly considered criminal by the Court of Instruction of Barcelona, as stated in the court order disseminated in the media."
Barcelona - who deny any wrongdoing - issued a statement in reply, saying Sevilla's actions were "an attack against the Catalan institution and an unacceptable offence".
Source: BBC