Joseph Hughes, from Rhyl, north Wales, asked for a wig for Christmas and wears a dress when out with mum Sam Hughes, 41, as he makes the transition to becoming Ellie-Jo.
His mum said: "He is definitely more confident as Ellie-Jo and more content in himself.
"I just wanted to raise awareness because I had no idea about this until Joseph started acting more like a girl when he was two.
"I want to help other families feel as secure and comfortable with it as I am."
The proud mum-of-six said she leaves it up to Joseph to decide his gender.
Hughes said: "Joseph is the one who has made this choice - if I'd have dressed him up as a girl from the start then he wouldn't have had a clue - but all this has come from him and I just let him get on with it.
"Some days he'll come home from school and put a dress on, some days it'll be some a t-shirt and jeans.
"It's easier for him to dress up and paint his nails when he's indoors at the moment because he can still get a little embarrassed when someone notices his nails."
Hughes added: "He's started going out in a dress when he is with me so that'll prepare him for when he has to go out on his own and do it - he wants to back to school as a girl in September."
The full-time mum says she is sure it is not a phase after taking Joseph to see specialists at CAMHS (Child and Adult Mental Health Services) and a children's clinic in Rhuddlan, north Wales.
The specialists said they want to wait until Joseph's hormones develop by the time he is 11 to see if it is a lasting choice.
But Hughes has no doubt in her mind that Joseph has gender dysphoria.
Hughes said: "What child at the age of nine chooses to go outside dressed as a girl? As an adult that would not be normal - I wouldn't do that - that's bravery.
"He's my son and I will back him all the way whatever he wants to do.
"If he turns around in five years' time and says I want to be a boy or I want to make the change permanent then I will never stand in his way."
Useful websites and helplines:
- Beaumont Society is a national self help body run by and for the transgender community | 01582 412220
- The Gender Trust supports anyone affected by gender identity | 01527 894 838
- Mermaids offers information, support, friendship and shared experiences for young people with gender identity issues | 0208 1234819
- LGBT Youth Scotland is the largest youth and community-based organisation for LGBT people in Scotland. Text 07786 202 370
- Gires provides information for trans people, their families and professionals who care for them | 01372 801554
- Depend provides support, advice and information for anyone who knows, or is related to, a transsexual person in the UK.