Under the leadership of Nigel Farage, the right-wing party achieved the rarest of political feats in securing its entire aim with the fulfilment of the Brexit vote, after nearly two decades of campaigning.
Anne Marie Waters, who has called Islam "evil" and has links to the far right, finished second in the seven-candidate race with 2,755 votes.
Speaking at the UKIP conference in Torquay, Mr Bolton urged delegates to "rally around the party".
A source told express.co.uk: "If Anne Marie Waters win the party won't exist in its current form in two years". He said Prime Minister Theresa May's Conservative-led government had so far failed to deliver on the Brexit mandate that voters wanted.
Farage temporarily returned to the leadership and was then replaced by Paul Nuttall MEP, who promised to win pro-Brexit Labour-held constituencies in the north of England. Bolton, who won with 30pc of the vote, used his acceptance speech to make clear that Brexit is Ukip's priority: 'Brexit is our core task however, it is not the end of the line'.
Tatiana Smurova-Bolton gave birth on platform 13 of the St Pancras, a UKIP spokesperson confirmed, and the couple subsequently named their daughter Victoria.
He has said he will have conversations with Ms Waters, Mr Farage and Mr Banks about their futures with the party.
His election will be met with a sigh of relief by many of Ukip's top command. Bolton reportedly said he was "fine" with the new design.
"If you look at the things I've done, you'll see a certain degree of endurance there, both physical, emotional and political", he said.
Under Nuttall the party introduced a so-called "integration agenda" aimed at Muslims, including a proposed ban on wearing a full-face veil in public.
Ukip grandee Nigel Farage welcomed his appointment as party chief, calling him a "man of real substance".
The party has been riven by splits and disagreements, one of which resulted in MEP Steven Woolfe being taken to hospital after a fight with another Ukip MEP.