The London Fire Brigade said that five of the 14 were taken to hospital and some 400 guests were evacuated to a nearby hotel after the blast caused extensive damage to the basement and ground floor.
The hotel chain said in a statement that 12 Hyatt employees were injured and that no guests were hurt. Five cars on a neighbouring street were also damaged.
"Hyatt's top priority is the safety and well-being of our guests and associates, and we are currently working to provide guests with accommodations while we evaluate whether the hotel suffered any significant damage," the company said in a statement.
The explosion at the five-star Churchill Hyatt Regency Hotel took place just before midnight Friday.
Six fire engines and 35 firefighters responded, together with rescue and hazardous materials teams. Officials say the cause of the blast is being investigated, but a gas leak is suspected.
The luxury West End hotel has 434 rooms and suites.