Nicaraguan Winston Campos has been lined up to fight Taylor at the Hydro in Glasgow on Saturday after a heavy cut was cited as the reason for the withdrawal of Mexican former three-weight world champion Soto.
Campos, 25, has won 30 and lost three of his 38 professional fights, all but two of them in his home country. His most recent defeat came in 2013 against former WBA lightweight champion Ismael Barroso and he won four of his five fights last year by knockout.
Blain McGuigan of Cyclone Promotions said: “We were informed that Humberto Soto had sustained a serious cut during a sparring session and that he would not be able to compete.
“We wish Humberto a full recovery.
“Josh now has to focus on Winston Campos, who is a hard-punching southpaw full of confidence and he will be hell-bent on taking Josh’s title.”
The unbeaten Taylor became the first man to stop Mexican Miguel Vazquez in his previous defence and now has to adjust to a change in opponent.
“It came as a bit of a shock but these things happen in boxing,” the Prestonpans fighter said.
“I wish Humberto Soto all the best in his recovery but now I’m one hundred per cent focused on defending my title. I’m confident I can put on a career-best performance next weekend at the SSE Hydro.”
Campos added in a statement: “I’m delighted to get this opportunity. I was in training for another fight when I got the call. I’m coming to Glasgow to shock the world.”