A transgender police officer said he was "humbled and proud" to become the first person to raise the rainbow LGBTI flag outside Brisbane's police headquarters today.

The historic first happened as part of International Day Against Homophobia and Transphobia, and was aimed at demonstrating the Queensland Police Service's (QPS) support for the LGBTI (lesbian, gay, bisexual, transgender and intersex) community.

After raising the flag, Constable Mairead Devlin, 22, said the gesture was the product of hard work within the organisation, but that more always needed to be done.

Constable Mairead Devlin, and the LGBTI flag outside the Brisbane police headquarters. (9NEWS)

The 22-year-old said he joined the service in 2013 and transitioned from female to male from late 2014.

"I transitioned at work, in the same workplace, and it's been really smooth sailing compared to what I expected," he said.

"For me, transitioning in the QPS, there's been a staggering amount of allies and identifying people that I've encountered, and I think maybe the general public aren't so aware of that sometimes."

Constable Mairead Devlin raising the flag. (9NEWS)

The flag raising was the "sum total of a lot of hard work internally within the organisation," Const. Devlin said.

"I felt humbled and proud – I didn't drop it, that was a concern – but I'm very glad to have been given the opportunity to raise it today."

Const. Devlin said the QPS' own LGBTI Support Network had been a great resource.

However, there was always more to be done, particularly in terms of education, he said.

"From the day I came out management have been very supportive, I'm sort of yet to come across someone who have expressed a negative opinion of what I'm doing," he said.

"I think any negative attitudes that I've encountered have just come down to a lack of education..."

QPS LGBTI Support Network co-ordinator Sergeant Michael Gardiner (far right), with other supporters. (9NEWS)

Support network co-ordinator Sergeant Michael Gardiner said the flag-raising may seem like a "simple and minor thing", but it was deeply meaningful to QPS' LGBTI staff.

"I wouldn't've thought, many years ago, coming out as a gay police officer that we would see this today, but I'm happy… by the crowd and the support we've got, especially from the commissioner and the senior executive, which has led to this very historical moment," he said.

"[LGBTI staff] see this as a massive step forward for us for acceptance and I know it reflects the diversity and inclusiveness of the service," he said.

Acting Deputy Commissioner Mike Condon dismissed suggestions the flag-raising was tokenistic.

He said it had nothing to do with politics, and was rather a sign of QPS' valuing of diversity.

"It's important for two reasons; first of all, so we're seen as a workplace of choice, and secondly, we represent the diverse community we serve," he said.

"If we don't understand that diversity within our organisation how can we better serve our people across the state?"

Australian Christian Lobby Queensland director Wendy Francis had criticised QPS for engaging in "rainbow politics".