The £4.2m Pitmaston House development in the Moseley area of the city was adorned with large blue rosettes and ribbons but local media reported there was a heavy security presence.
Only invited guests were allowed to attend, and coaches were used to block the view from a nearby road.
The organisation’s leader gave a speech at the event, according to its website.
He said: “When that inaugural ribbon falls, so a curtain rises… and so it becomes every Scientologist’s responsibility to uplift England’s Salt of the Earth, thereby turning an industrial revolution into a spiritual revolution.”
The Church of Scientology, which bought Pitmaston House in 2007, claims to have a core following in the UK’s second most populous city, and plans to use the building to expand its operations through the Midlands and beyond.
Former Scientologists were among those who protested the opening of the building.
“People don’t understand what’s going on in their local area and that’s very frightening,” William Drummond, a former long-time member, told the Birmingham Mail.
“The main motivation for them is money, property and expansion – and that’s evident here.”
Another former Scientologist, Adrian Bailey, told the newspaper: “What annoyed me the most was that they always asked for money. And with all the secrecy, it’s not surprising people think it’s a cult.”