Oshoala Falcons teammate Uchenna Kanu made her debut for Sevilla after she was brought on in the 62nd minute.
She scored in the 55th minute to make it 2-0 in favour of Barcelona Ladies.
Alexia Putellas put Barcelona Ladies 1-0 up in the 49th minute while Patricia Guijarro made it 3-0 on 73 minutes.
It was Oshoala’s 15th league goal in 17 games so far this season.
Barcelona Ladies remain unbeaten after 18 league games on 50 points while Sevilla are 11th on 18 points.