A Brand Voice System Prompt For Your Company

Every email, tweet, landing page, and support reply shapes your brand. If each one sounds like a different person wrote it, your brand feels confused. If they all sound the same, your brand feels real. The trick is a brand voice system prompt — a reusable instruction you paste in front of any AI task to lock the voice.

• Tone words (friendly, direct, warm, technical, casual, sharp)
• Words you always use (specific vocabulary)
• Words you never use (jargon you hate)
• Sentence structure preferences (short, long, mixed)
• Example of how you sound (a few real sentences)
• Who you sound like (voice similar to X writer or brand)

The template

You are the writing assistant for [Brand Name], a [one-sentence positioning]. AUDIENCE: [specific customer — include age, job, context] TONE: [3-5 adjectives]. Think [writer/brand comparison 1] crossed with [writer/brand comparison 2]. ALWAYS: - Use short sentences by default; occasional long sentences for rhythm - Speak directly to the reader ("you," not "users") - Use specific examples instead of generic claims - [Any domain-specific rule] NEVER: - Use "revolutionary," "seamless," "cutting-edge," or "leverage" (as a verb) - Open with "In today's fast-paced world" - Hedge with "arguably" or "perhaps" - [Any domain-specific rule] SIGNATURE PHRASES: [3-5 phrases unique to your brand] EXAMPLES OF WHAT GOOD LOOKS LIKE: [Paste 2-3 real sentences you wrote that capture the voice] When drafting content, internalize this voice before generating. If my request conflicts with the voice, ask me before writing.

How to discover your voice in 30 minutes

1. 1Write 5 real sentences about your product, in your own voice, no AI
2. 2Read the 3 newsletters / tweets / pages you wish you sounded like
3. 3Note 3-5 brands you do NOT want to sound like (this is as important as the first)
4. 4Pick 5 tone words that capture the intended feel
5. 5Draft the system prompt using the template above
6. 6Test: paste it and generate 3 pieces. Edit the prompt until they feel right.

Where to use it

The 'AI smell test'

AI-generated content has telltale smells: 'delve,' 'it's important to note,' 'in conclusion,' 'leverage,' 'revolutionize,' 'seamless.' Add these to the NEVER list. Also banned: any sentence that could come from any brand. The voice test is 'would a random reader know this is specifically from us?' If the answer is no, the voice is too generic.

What 'good' looks like

A good brand voice prompt is 200-400 words, lives in one known place, and gets used for every piece of content. When a stranger reads three pieces from your brand, they can tell it's the same voice. When you outgrow the prompt, you update it — not rewrite from scratch. Voice compounds; consistency is the hidden marketing asset.