How to make ChatGPT use your brand voice.
To make ChatGPT use your brand voice, give it rules instead of adjectives, real examples of right and wrong, your approved facts and forbidden claims, and keep all of it in one place every chat reads, such as a custom GPT or a Project. Then test it blind. Here is the method I use for clients, step by step. Built for CEOs, founders and marketing leads at B2B tech companies.
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What your brand voice file needs.
The same contents work for ChatGPT, Claude and Copilot. Only where you load them differs.
- Who you write for, in one line
- Voice rules you can check: length, words, rhythm
- Words you always use and words you never use
- 3-5 right and 3-5 wrong examples, with reasons
- Approved facts, numbers and product names
- Claims nobody may make, like unapproved guarantees
Six steps to a ChatGPT that sounds like you.
The method, not a magic prompt. Prompts change with every model; these steps do not.
Write rules, not adjectives
“Friendly and professional” means nothing to a model. “Sentences under 20 words, numbers before adjectives, no exclamation marks” does.
Show right and wrong
Give 3-5 real texts that sound like you and 3-5 that do not, each with one line on why. Models learn faster from contrast.
Add facts and forbidden claims
Most off-brand AI text is wrong facts, not wrong tone. List what is true, what is coming and what nobody may promise.
Put it where it persists
A custom GPT or a ChatGPT Project keeps the rules for every chat. Pasting them each time does not scale to a team.
Test blind
Ask the same questions with and without the rules, and have someone who does not know which is which judge the answers.
Version it
When the brand changes, update one source. Every teammate's ChatGPT, and Claude, should read the same file.
Why most brand voice prompts stop working.
A long voice prompt works for a week. Then someone on the team uses a different chat, a new model version reads it differently, or the facts change and nobody updates the prompt. The voice was never the hard part. Keeping one source of truth that every tool reads is.
That is why I build brand voice for AI as a system, not a prompt: rules, examples, facts and a self-check, loaded the same way into ChatGPT and Claude. The setup per teammate takes about a minute. I do not publish the kit files themselves; the method above is enough to start on your own. When you want it built and tested, see ChatGPT brand guidelines and brand guidelines for Claude.
Brands whose AI writes on-brand.
Deepsea Networks: before, 8 of 16 AI drafts broke a hard brand rule. With the brand system loaded, 0 of 26 (my blind test, 08.10.2026).
When I build it for you.
10 days, tested on your own drafts.
Read the brand
Guidelines, site, decks and real posts. I list what AI gets wrong today.
Write the rules
Voice, facts, forbidden claims and visual tokens, in the form models follow.
Build and test
Kit, skill and templates, then a blind test with and without them.
Hand over
A 1-minute setup for every teammate and a short video.
Tell me about your brand. Get a plan in a minute.
Three taps, then my plan for you: the package, the days and what you get. If it fits, I write a fixed-price proposal in 2-8 hours. One field at the end, email or WhatsApp. Nothing is binding.
Free first step: AI Mirror shows what ChatGPT says about your company today, and the AI-Ready Check scores your brand in 2 minutes.
A voice prompt, next to a voice system.
| One long prompt | A voice system | |
|---|---|---|
| Lasts | Until someone forgets it | Loaded in every chat |
| Facts | Usually missing | Approved list |
| Team | Each person their own | One source for all |
| Proof | A feeling | A blind test |
Not right? Full refund.
You see the strategy and the first design direction before anything else gets built. If it doesn’t feel like your company, tell me within 24-48 hours and you get back everything you paid.
- Full refund if the first direction isn’t right
- Every file and key is yours from day one
- Fixed price, nothing added unless you ask
Written into every proposal.
Straight answers.
ChatGPT is a trademark of OpenAI, Claude of Anthropic. Vizura Studio is an independent studio, not affiliated with either.
Can I train ChatGPT on my writing style?
You do not retrain the model. You give it your rules and examples as persistent instructions or files, and it follows them.
Custom GPT or Project?
A custom GPT is easier to share with a team; a Project is good for one person's ongoing work. Both keep the instructions between chats.
Why does ChatGPT still sound generic?
Usually the voice is described with adjectives and there are no wrong examples. Rules and contrast fix most of it.
Does the same file work in Claude?
Yes, with small changes. In Claude it can be a skill or a Project. See brand guidelines for Claude.
Will you share your prompt?
No, but the six steps above are the method. When you want it built, tested and kept current, that is Brand OS Portal.
Want ChatGPT to sound like your brand, tested? Tell me in a minute.
Proposal in 2-8 hours. Or 15 minutes on a call, and if it's not a fit, I'll tell you.