Andrew Strauss's side will face the Proteas at Lord's this week without Pietersen after he was left out of the team for allegedly sending derogatory texts about the captain to players in the South African squad.
However, Swann has suggested that England's form in the shorter format since Pietersen's retirement proves that they can deal with his absence.
The spinner told The Sun: "We need to pull in the same direction, not 10 us doing it and one of us not.
"Just because you lose one player, it doesn't necessarily make you a weaker team.
"In fact, since Kevin retired from limited-overs cricket, we are unbeaten in all matches in the shorter formats."
Swann is expected to return at Lord's on Thursday after England decided to not play a spinner during the second Test at Headingley.