Tired of disconnected data and clunky marketing workflows?

 If your CRM and email platforms aren’t speaking to each other, you’re leaving money on the table.

This guide shows you how to integrate HubSpot with Klaviyo seamlessly—so you can automate smarter, personalise better, and turn leads into loyal customers. You'll streamline campaigns and drive real retention by combining HubSpot’s rich contact data with Klaviyo’s email and SMS power.

From manual CSV uploads to automated tools like Zapier, Outfunnel, and the Klaviyo API, we’ll walk you through the best setup for your business—plus highlight easy-to-miss steps (like syncing unsubscribes) that protect your list and performance. Whether you're in marketing or dev, this guide helps you connect the dots and boost ROI.

Why HubSpot x Klaviyo = Smarter Marketing

Want better results from your campaigns? Syncing HubSpot with Klaviyo gives you a full view of each customer, letting you automate more relevant emails and track every step of the buyer journey.

Centralizing Customer Data:

Businesses can create unified customer profiles by syncing HubSpot (CRM) with Klaviyo (ESP). This synergy ensures a holistic view, which is crucial for effective targeting and personalisation. For instance, combining CRM data with email engagement metrics allows for better customer insights.

Take your segmentation to the next level with our guide to 3 Klaviyo Segmentation Strategies That Actually Drive Sales

Triggering Personalized Automation:

Using lifecycle data from HubSpot, such as lead stages (e.g., Lead, Marketing Qualified Lead, Sales Qualified Lead), businesses can trigger specific email flows in Klaviyo. This automation ensures timely and relevant communication, enhancing customer engagement and conversion rates.

Want to build flows that turn first impressions into conversions? Learn from our 8 Essential Klaviyo Flows to Boost Customer Loyalty

Measuring Full Funnel ROI: 

Syncing data improves attribution, enabling businesses to track the customer journey from initial contact to revenue generation. A visual suggestion, a funnel diagram showing HubSpot → Klaviyo → Flow → Revenue, was proposed to illustrate this process, emphasising end-to-end visibility.

Methods to Integrate HubSpot and Klaviyo

There’s no one-size-fits-all integration. This section breaks down four ways to connect HubSpot and Klaviyo—manual or automated—so you can choose the best setup for your team’s size, skills, and goals.

• Klaviyo API: This method allows custom and real-time syncing for advanced users with development resources. It has a high setup time (2–4 hours), full automation depth, and is free but requires developer time, making it best for custom workflows and large data syncs.

• Manual CSV Sync: Best for one-time or infrequent updates, involving exporting contacts from HubSpot and importing them into Klaviyo via CSV. This method is straightforward, with low setup time (15–30 minutes) and no cost, making it easy for users without technical skills.

• Zapier Integration: Automates syncing of contacts and updates using Zapier's platform, which connects apps without coding. It has a medium setup time (30–60 minutes), moderate automation depth (trigger-based), and is paid based on Zapier plans. It's ideal for businesses seeking automation without developer support.

• Outfunnel Integration: A purpose-built tool for syncing CRM and email tools, offering high automation depth (CRM - ESP syncing) and easy use. Setup time is medium (20–45 minutes), and it requires a paid subscription, suitable for teams needing real-time sync with minimal setup.

Comparison Table for Integration Methods

Confused about which route to take? Our Klaviyo Salesforce Integration Simplified breakdown explains what to look for in any CRM-ESP connection.

Step-by-Step – Manual HubSpot to Klaviyo Integration

If you're migrating contacts manually, follow this exact checklist. From exporting active lists to suppressing unsubscribes, this section covers every detail, so nothing falls through the cracks.

Pre-Migration Setup: Create These Lists in HubSpot

Before exporting any data, build these contact lists:

• Everyone – Active: All active contacts → Upload into Klaviyo Email List

• All Unsubscribes: Export and upload into the Klaviyo Suppression List

• 7-, 14-, 30-, 60-Day Engagement: Keep these to warm up your list with Klaviyo campaigns

Migration Checklist

1. Export active HubSpot contacts into a CSV file

2. Format the CSV file for Klaviyo

3. Import the CSV file into a Klaviyo list

4. Export HubSpot unsubscribes

5. Upload unsubscribes into the Klaviyo Suppression List

6. Export 7-day, 14-day, 30-day, and 60-day engagement lists

7. Migrate HubSpot email templates to Klaviyo

8. Sunset your HubSpot account (forms + automations)

9. Send your first campaign in Klaviyo

Detailed Step-by-Step Process

1. Export Contacts from HubSpot

• Go to Contacts > All Contacts → Use Options > Export View

• Choose CSV and export All properties

  
  

2. Format the CSV Files

• Ensure "Email" is the first column header

• Include "First Name", "Last Name", and any custom fields

• Remove extra rows above the headers

• Format date fields: YYYY-MM-DD HH:MM:SS or MM/DD/YYYY HH:MM

  
  

3. Import to Klaviyo

• Go to Audience > Lists & Segments → Select list

• Click Manage List > Import Contacts → Upload CSV

• Map fields and confirm consent status

  
  

4. Export HubSpot Unsubscribes

• Go to Contacts > Lists > Create List in HubSpot

• Name your list (e.g. "All Unsubscribes")

• Select Contact-based and choose Active list

• Set filter: Unsubscribed from all emails = True

• Save the list and export it with only the Email field selected

• Format the CSV to include a single "Email" column only

  
  

5. Upload Unsubscribes to Klaviyo

• Go to Audience > Suppressed Profiles in Klaviyo

• Click Upload File → Select your unsubscribe CSV

• Click Upload Suppressions

6. Export Engagement Lists

• Create separate active lists in HubSpot filtered by the Last marketing email open date after [X date]

• Export lists for 7, 14, 30, and 60 days of engagement

• Use these to warm up your sending domain in Klaviyo

  
  

7. Rebuild Email Templates in Klaviyo

• Use Klaviyo’s drag-and-drop editor to rebuild templates

• Or, upload HTML versions exported from HubSpot

8. Sunset HubSpot Account

• Recreate HubSpot forms in Klaviyo

• Rebuild automation as Klaviyo flows

• Turn off HubSpot workflows and growth tools

9. Send Your First Campaign

• Start with your 7-day engaged list

• Monitor performance and increase sends gradually

Source: Klaviyo

Real-World Use Cases

Not sure how the integration helps in practice? These real examples show how different businesses—from DTC to B2B—use synced data to power welcome emails, lifecycle campaigns, and personalised SMS flows.

• Lead Nurturing for DTC: 

Sync new HubSpot leads to Klaviyo and trigger a welcome flow, ensuring new customers receive timely engagement. For instance, a new lead can be added to a Klaviyo list and receive an automated welcome email series.

• B2B Lifecycle Marketing: 

Sync lifecycle stages from HubSpot (e.g., Lead, MQL, SQL) to power Klaviyo automation, such as sending stage-specific emails. This ensures sales teams can nurture leads based on their progression, improving conversion rates.

• Email-SMS Personalisation: 

Segment by HubSpot properties like industry or lead score to personalise email and SMS flows in Klaviyo. For example, high-scoring leads in the tech industry can receive tailored offers, enhancing relevance and engagement.

Looking to drive repeat sales with your flows? Don’t miss our Post-Purchase Email Examples That Actually Boost Loyalty

Common Integration Mistakes & How to Avoid Them

Many brands trip up when syncing HubSpot to Klaviyo. This section highlights the most common errors—like missing unsubscribes or broken field mappings—and shows you exactly how to avoid them.

Worried about list fatigue or deliverability drops? Our guide to Klaviyo Sunset Flow: Keep Your List Clean & Engaged shows how to manage inactive profiles effectively.

Section 6: Best Practices for Syncing Contacts

To get the most from your sync, accuracy is key. Learn how to map fields correctly, avoid duplicates, and keep your lists clean with simple tips that make a big difference to your automation and segmentation.

Purpose:
Help users set up reliable, error-free contact syncs between HubSpot and Klaviyo.

• Field Mapping: Ensure HubSpot fields map correctly to Klaviyo properties. For example, HubSpot's "First Name" maps to Klaviyo's "first_name," and "Contact Owner" can be a custom property. A suggested field mapping table is:

  
  

• Ensure Data Accuracy: Validate email addresses to avoid sync issues, handle duplicates by merging based on email, and conduct regular sync audits to maintain data hygiene. For instance, ensure no missing or inconsistent emails to prevent sync failures.

• Manage Updates & Duplicates: Choose between real-time (e.g., via API or Outfunnel) or batch updates (e.g., manual CSV) based on needs. For duplicates, implement merge logic, such as prioritising the most recent record, to prevent data redundancy.

Keep your data fresh and compliant. Here’s your Step-by-Step Email Deliverability Checklist

FAQs

1. Can I use HubSpot forms with Klaviyo directly?

•  No forms must be recreated using Klaviyo or a supported third-party tool for proper syncing.

2. How often does data sync using Zapier or Outfunnel?

•  Zapier syncs based on your trigger setup (often instant or delayed), while Outfunnel provides near real-time syncing depending on your plan.

3. Will syncing affect my existing Klaviyo flows?

•  If flows are triggered by list updates, yes. Always turn them into drafts before importing new contacts.

4. Can I sync only specific contacts from HubSpot?

•  Yes—use segmented lists in HubSpot (e.g., engaged contacts or leads only) before exporting.

5. Is it possible to keep HubSpot and Klaviyo running at the same time?

•  Yes, but it's risky. You may double-email contacts or skew reporting. Fully migrate when you're ready.

Conclusion

If your HubSpot and Klaviyo accounts aren’t connected, you're wasting time—and losing conversions. Manual exports lead to outdated lists, broken automation, and poor personalisation. 

But with the right setup—whether via CSV, Zapier, Outfunnel, or the API—you can build an integrated system that works behind the scenes to move leads down the funnel. 

This guide gives you every step and option, so you can sync your data, launch smarter campaigns, and finally build retention flows that convert.

Key Takeaways:

• Why Integrate: Unlock smarter automation and personalised flows with centralised data.

• Integration Options: Pick the best sync method—manual, Zapier, Outfunnel, or API—based on your needs.

• Manual Migration Steps: Follow a full checklist to ensure clean, compliant data transfer.

• Real Use Cases: See how DTC and B2B brands trigger flows from HubSpot data.

• Avoid Mistakes: Double-check field mapping and unsubscribes to stay compliant.

• Best Practices: Keep data clean with routine audits, proper formatting, and smart segmenting.

Ready to fix those HubSpot-Klaviyo sync issues? 

Let us clean your data, resolve integration hiccups, and optimise your automation. Click here and claim your free expert audit now, and level up your performance