The couple's three sons – Brooklyn, 11, Romeo, 8, and Cruz, 5 – were said to be "very excited" about having a new brother or sister.
The announcement was made after weeks of speculation the family could return to the UK and began a debate on whether the child could be their longed-for baby girl, which fashion designer Victoria, 36, said in an interview she had given up all hope of.
Former England captain David, 35, was linked with a move to Tottenham Hotspur but manager Harry Redknapp admitted yesterday the deal "looked like a no-goer".
The Beckhams are back in the UK, where they are expected to stay until February when David returns to LA Galaxy and Victoria attends the New York Fashion Week.
Their spokeswoman said both their families were "delighted" with the news.
A message on David Beckham's Facebook page said: "Victoria and I are expecting our fourth child this summer. The boys are very excited about the arrival of a new brother or sister."
Amanda Holden, who is also pregnant, said on Twitter: "Great News that the Beckham's are expecting their 4th child! Hope they get a pink one!"