"I am absolutely sure that she gave me her permission," Rubiales told the court in Madrid where he is standing trial on Tuesday.
"In that moment it was something completely spontaneous."
Rubiales, 47, is accused of sexual assault for kissing Hermoso on the mouth and then attempting to coerce her - with the help of three other former football federation officials - into publicly saying the kiss at the 2023 World Cup awards ceremony in Australia had been consensual.
He has denied the charges, insisting the kiss was consensual while Hermoso has said it was not.
"I asked her if I could give her a little kiss and she said 'okay'," Rubiales said on Tuesday.
"I'm totally sure (she gave consent)."
Hermoso said on the first day of the trial last week that she did not consent.
Rubiales said he admits the kiss was a mistake, saying he behaved more as a former player than as the president of the institution that he was.
"Hermoso knows that I asked her and she contested me," Rubiales said.
"I apologised for my behaviour because it was not adequate. Being in that position I should have had cold blood and not let myself be taken away by emotions. Surely I should have behaved more in an institutional plan."
Rubiales said Hermoso was asked to downplay that kiss because there was an institutional crisis affecting the federation and it was normal for officials to try to diffuse the situation.
He said he never asked anyone to pressure Hermoso.
He said Hermoso at the time was not making a big deal about the kiss.
Hermoso and her teammates gave different versions during their testimony, saying that the player was badly affected by the kiss and pressured to downplay what happened.
An expert on lip reading also testified on Tuesday, saying that Rubiales asked Hermoso, "Can I give you a little kiss?".
Asked whether he normally kissed people on the lips, Rubiales said the occasion and the fact he had known Hermoso for a long time warranted it.
He said he would do something similar with a male player or one of his daughters.
"You don't win a World Cup every day," he said.
"When I see my daughters I don't give them a peck but on New Year's Eve I give them a peck."
Witnessed by millions of television viewers and an entire stadium in Sydney during the awards ceremony following the Spanish women's team's victory in the 2023 World Cup, the ensuing uproar gave momentum to a "Me Too" movement in which female players were combating sexism and striving for parity with their male peers.
The prosecution is seeking two and a half years' prison for Rubiales, although in Spain those handed sentences under two years can usually escape incarceration by paying damages instead if they do not have prior convictions.
Alongside Rubiales, former women's team coach Jorge Vilda, former Spanish football federation (RFEF) sporting director Albert Luque and the RFEF's former head of marketing Ruben Rivera are also on trial for their suspected roles in pressuring Hermoso.
They have denied the charges.
After Spain beat England in Sydney on August 20, 2023, Rubiales clutched his crotch in celebration on the final whistle while standing near Spain's Queen Letizia and her daughter Princess Sofia.
Later, during the medal presentation, he appeared to lift Hermoso off her feet then grabbed her by the head and pulled her toward him to kiss her on the lips.
Testifying last week, Hermoso said she did not agree to the kiss and that the furore had tainted what should have been one of the happiest days of her life.
A verdict in the case is expected in March, about a month after witness testimony ends.
with AP
