Klaviyo Sign-Up Forms: Types, Setup and Fixes (2026)

Your sign-up forms decide who ends up in Klaviyo, and therefore what every flow downstream has to work with. They are also one of the few places in the account where a change on Monday shows up in the numbers by Friday. This guide covers the Klaviyo forms builder as it works in September 2026: the form types, how to set one up properly, SMS consent, embedding on Shopify, and the fixes for the most common problem of all, a form that won’t show.

For the strategy side (offers, timing and copy that convert), read our email popup best practices. This page is the Klaviyo-specific build guide.

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Klaviyo sign-up forms: the short version

Klaviyo has a native sign-up form builder with five form types (popup, flyout, full page, embed and banner). Forms can be multi-step, collect email and SMS consent, show coupons and teasers, target visitors by page, location, UTM, list membership or cart contents, and be A/B tested. Every submission writes to the customer’s Klaviyo profile and can trigger a welcome flow instantly.

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The five Klaviyo form types

From Klaviyo’s help centre:

Form type	What it is	Best for
Popup	A modal in the centre of the screen	Main list-growth form with an offer
Flyout	Slides in from a corner; visitors keep browsing	Softer asks, content pages, returning visitors
Full page	Covers the full screen	Mobile-first capture, launches, age gates
Embed	Sits inside a page section, such as the footer	Always-on capture; footer and landing pages
Banner	A bar at the top or bottom of the page, fixed or scrolling	Announcements; can open another form

Teasers, the small tab that reopens a closed form, work on popups, flyouts and full-page forms, but not banners.

Other form building blocks include coupon blocks, countdown timers, sign-up counters, review quotes and age gates. There is also a spin-to-win block (two to six slices, probabilities adding to 100%), and a dedicated back-in-stock form for Shopify and BigCommerce stores (one per account).

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How to build a Klaviyo sign-up form that converts

1. Set one goal per form

Decide what the form is for: email only, email then SMS, a quiz-style preference capture, or a specific landing page. One form trying to do everything converts worse than two forms doing one job each.

2. Use multi-step for email and SMS

Ask for email on step one, then phone number on step two. You capture the email even if they skip the phone step, and the SMS ask lands after a small commitment. Add steps with ”+ Step” in the editor.

3. Keep fields to a minimum

One field per step. Collect preferences (product interest, skin type, goal) as buttons on a later step rather than extra fields up front.

4. Style it to your brand, then check mobile

Most of your traffic is mobile. Preview on a real phone: close button easy to tap, input field tall enough, no text smaller than body copy. Our popup best practices covers the mobile details, including Google’s intrusive interstitial rules.

5. Set targeting and behaviour

Klaviyo lets you control:

• Timing: delay, scroll percentage, exit intent.
• Frequency and dismissal: how often it shows and what happens after closing.
• Device: separate desktop and mobile versions.
• Audience: location, list or segment membership, URL, UTM parameters and cart contents.
• Display priority: which form wins when several could show.

The single most valuable rule: don’t show your sign-up popup to people who are already subscribed. Exclude existing list members so your customers aren’t asked to subscribe again.

6. Connect it to a flow

Point the form at a list that triggers your welcome series, and deliver whatever the form promised in the first email, immediately. Our welcome series framework covers what should follow.

7. Publish and test

Set the form live, test it in a private browsing window on desktop and mobile, submit a test email, and check the profile, list and flow trigger in Klaviyo.

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Collecting SMS consent in Klaviyo forms

Klaviyo gives you three main ways to capture SMS subscribers in a form:

• Phone field on a second step of a multi-step form, with the required consent language.
• Tap-to-text, a mobile-only two-step opt-in where the visitor taps a button and sends a pre-filled text. Because the subscriber sends the message, the list can be single opt-in. It doesn’t work with branded sender IDs.
• Smart Opt-in, which uses a one-time code with autofill on iOS and Android. It requires a paid SMS plan, and forms using it stop working if you downgrade.

Consent rules for SMS vary by country and are strict in the US. Make sure your form’s consent text matches your programme, and get the fundamentals right with our SMS marketing approach before scaling.

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A/B testing Klaviyo forms

Klaviyo’s form A/B tests can compare teaser, timing, coupon or content, with up to four variations. Test one variable at a time and in order of impact: offer first, then headline, then timing, then design.

Klaviyo also has an AI “optimization test” that experiments with display timing and auto-applies the winner, but it needs 400,000+ total profiles, so most brands won’t have access. More on Klaviyo’s AI tools in Klaviyo AI features, tested.

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How to embed a Klaviyo form

On Shopify

1. In Klaviyo, create an Embed form and set it live.
2. In Shopify, check the Klaviyo app embed is enabled in your theme’s app embeds.
3. Copy the form ID from the form’s embed code in Klaviyo.
4. In the Shopify theme editor, choose Add section → Apps → Klaviyo Embedded Form, and paste the form ID.
5. Place it in the footer to show on every page, or in a specific template for landing pages.

Popups, flyouts, full-page and banner forms don’t need embedding: they display automatically once the Klaviyo app embed (and onsite tracking) is active and the form is live. If you haven’t connected the store properly yet, start with how to connect Klaviyo to Shopify.

On other sites

Install Klaviyo’s onsite JavaScript (Klaviyo.js), then paste the form’s embed code where you want the form to appear.

In an email

You can’t reliably embed a working form inside an email, because most email clients don’t support interactive forms. Link to a page with an embedded Klaviyo form instead.

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Why isn’t my Klaviyo form showing? The fix list

From Klaviyo’s troubleshooting guidance and our own audits, check these in order:

1. The form isn’t live. Draft forms don’t display.
2. Onsite tracking isn’t installed. On Shopify, the Klaviyo app embed must be switched on.
3. You’ve already seen it. Klaviyo cookies browsers for a year after a form is closed or submitted. Test in a private window.
4. Display rules are too strict. All “show based on rules” conditions must be met at once.
5. URL targeting doesn’t match the page you’re testing.
6. Wrong or edited embed code for embed forms.
7. Ad blockers can stop forms loading.
8. Consent settings. With Shopify’s customer privacy settings, visitors in the EU, EEA, UK and Switzerland who haven’t consented aren’t identified.
9. More than one Klaviyo account is connected to the site.
10. Site CSS overrides using !important can hide or break the form.
11. Internet Explorer. Klaviyo forms don’t render there.

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Bot protection

Klaviyo automatically adds bot prevention, including CAPTCHA, to forms that collect email or phone numbers or show coupons. The CAPTCHA only appears for suspicious visitors, so genuine shoppers shouldn’t see friction. If you’re seeing fake sign-ups anyway, add double opt-in for the affected source and check your list hygiene.

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Klaviyo forms on the free plan

The form builder is available on the free plan, but free accounts show Klaviyo branding at the bottom of forms. Removing it requires a paid plan. See what is Klaviyo for what else the free plan includes.

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Klaviyo forms vs third-party pop-up tools

Tools like Privy and Justuno offer extra display and gamification options, and can pass sign-ups into Klaviyo. The trade-off is another script on your site and another place where data can fall out of sync. For most brands, Klaviyo’s native forms are enough and keep everything on one profile. We compare the two approaches in Klaviyo vs Privy.

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Form ideas worth building

• Welcome popup with an offer, email step then SMS step.
• Exit-intent variant with a different offer from the main popup.
• Quiz or preference form that tags interests for segmentation.
• Footer embed as always-on capture.
• Back-in-stock form on sold-out product pages.
• Landing page embed for paid social traffic, tagged with the UTM source.

Our 8 list growth strategies for ecommerce goes deeper on each.

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The bottom line

Klaviyo’s form builder is strong enough that most brands don’t need a separate pop-up tool. The gains come from configuration: a real offer, multi-step email and SMS capture, sensible targeting, and a welcome flow that delivers on the promise immediately.

If your list growth has stalled, our list growth service builds and tests forms as part of a full capture strategy, and the free Klaviyo audit will show you what your current forms are costing you.

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Sources

Checked September 2026:

• Klaviyo, Web forms
• Klaviyo Help, Getting started with sign-up forms
• Klaviyo Help, Troubleshooting forms not appearing
• Klaviyo Help, Embed a form on Shopify
• Klaviyo Help, Tap-to-text
• Klaviyo Help, Smart Opt-in
• Klaviyo Help, Spin-to-win forms
• Klaviyo Help, Back-in-stock forms
• Klaviyo Help, A/B testing forms
• Klaviyo Help, Free plan branding