Accelerate your Power BI report development with JSON theme files

Have you ever spent hours fine-tuning fonts, colors, and visual settings in your Power BI reports ? What if you could automate all of that and focus solely on insights ?

That's where using JSON custom theme files will help you ! This functionality let you build personnalized design in minutes — not hours ! All your report formatting can be done by applying consistent design rules, all from a single JSON file.

Why is design important in a Power BI report ?

A good design in reporting isn’t just about aesthetics — it’s about clarity, usability, and trust. A well-styled dashboard help your audience find their answer faster, making key insights stand out from the rest and reinforces the authority of the data being presented. The problem is that still too many Data Analysts (and I used to be one of them...) are fine-tuning their Power BI reports manually everytime they build a new one. This approach is not only time-consuming (as it usually takes several hours to fine-tune a report) but also introduce inconsistencies between different reports and even between pages and visuals within the same report.

But, what is a JSON theme file in PowerBI?

A JSON theme file is a simple text file that defines the look and feel of your Power BI report. It sets parameters for :

• Color palettes

• Fonts and font sizes

• Background and foreground colors

• Visual styles (like borders, shadows, titles)

• Accent colors for tables, cards, KPIs, and more

With a theme file, all your visuals inherit the same design by default — no manual styling needed.

Why use a JSON theme file ?

1 - because it accelerates your report development. When creating a new report, you can apply a pre-defined JSON theme file with just a few clicks. Instead of configuring every element individually, you can simply load the theme file, and the styling rules will be automatically applied to all the elements of the report. This reduces the time spent on design setup, allowing you to focus more on data analysis and the content of the report itself

2 - to stay aligned with your corporate guidelines. Whether you're building for marketing, finance, or another team, a JSON theme ensures your reports :

• Match your company’s styling rules (e.g. brand colors and fonts)

• Feel consistent across teams and departments

• Look clean and trustworthy

3 - for an easier collaboration and sharing. JSON theme files are easily shareable, making them ideal for teams working on the same set of reports. Once you define the theme file, you can for example host it in a central repository such as a SharePoint folder, a Microsoft Teams group or either in a shared disk drive. The goal is to share it among team members and ensuring everyone works with the same visual design. This consistency is particularly important in large organizations where multiple people might be working on different reports but need to ensure they remained aligned to the same brand guidelines.

4 - for an improved user experience. A professional, consistent design improves the overall user experience. When users access your Power BI reports, they expect them to have a professional, cohesive look. JSON theme files help achieve this by providing a structured way to define visual elements. Reports will feel more clean which ultimately leads to a better user experience.

How to create and use a JSON theme in Power BI

1 - Create a JSON theme file. There are several ways to create JSON theme files. I recommand you to visit the official Power BI website to get more all the technical details about this functionality. If you don't want to spend to much time on developing the theme file or lack knowledge to do so, there are multiples website that allows you to personnalize and downloads files, such as https://powerbithemegenerator.bibb.pro/.

2 - Import the theme in your Power BI report. To do so, you will need to :

1. Open your report with Power BI Desktop

2. Click on :  View > Themes > Browse for themes

3. Select your .json file

4. Surprise ! Your new theme has been successfully uploaded !