The centre is the first of six which are being constructed by the British government as part of the effort to stop the spread of the disease.
The UK's Disasters Emergency Committee says it has raised £13m for tackling Ebola, a week after its appeal launch.
The DEC, which is made up of 13 British aid charities, is helping to run treatment facilities and care centres.
The British Red Cross's Ebola response manager, John English, described the British public's response as "very generous" and said he hoped it would continue.
Meanwhile in the UK, Manchester Airport has begun screening passengers arriving from the worst-affected countries.
The facility at Kerry Town south of the capital Freetown includes a new blood testing laboratory. Six hundred more beds are planned at UK centres around the country in the coming months.
The centre also provides dedicated beds for infected healthcare workers and separate sites for confirmed and suspected cases.
Save the Children chief executive Justin Forsyth said there was a "race against time" to stop the disease spreading.