Google Workspace to Microsoft 365 Migration Guide 2026

Google Workspace to Microsoft 365 Migration: Enterprise Guide (2026)

Google Workspace → Microsoft 365 migration is a foundational 2026 enterprise modernization for regulated industries (healthcare, financial services, government, pharma) consolidating on Microsoft 365 for Microsoft 365 Copilot governance, Microsoft Compliance Manager industry framework attestation, Microsoft Information Barriers, and Microsoft Sentinel SOC integration.

EPC Group has delivered Google Workspace → Microsoft 365 migrations for Fortune 500 organizations since 2014.

TL;DR — Migration Methodology

Phase	Duration
1. Strategic Assessment	4-6 weeks
2. Microsoft 365 Foundation	4-12 weeks
3. Microsoft Entra Identity	4-8 weeks
4. Pilot Migration	4-8 weeks
5. Phased Cohort Migration	3-12 months
6. Microsoft 365 Copilot Enablement	3-6 months
7. Google Workspace Decommissioning	4-8 weeks
8. 90-Day Hyper-Care	90 days

Phase 1: Strategic Assessment

Activities

• Google Workspace inventory (mailbox count, Drive size, Google Apps Script automation)
• Microsoft 365 license sizing (E3 vs E5)
• Microsoft Entra-anchored identity strategy
• Microsoft Purview sensitivity label readiness
• Microsoft 365 Copilot governance scope
• Industry-specific compliance requirements

Deliverables

• Strategic Google Workspace → Microsoft 365 roadmap
• Microsoft 365 license recommendation
• Investment + timeline model
• Industry-specific compliance roadmap

Investment

• $50K-$200K (4-6 weeks)

Phase 2: Microsoft 365 Foundation

Activities

• Microsoft 365 tenant build (Commercial / GCC / GCC High)
• Microsoft Entra-anchored authentication
• Microsoft Defender XDR baseline
• Microsoft Purview sensitivity label taxonomy
• Microsoft Sentinel SOC integration
• Microsoft Compliance Manager industry framework attestation
• Microsoft Customer Lockbox (regulated)

Deliverables

• Microsoft 365 tenant operational
• Microsoft Defender XDR baseline
• Microsoft Purview sensitivity label library
• Microsoft Sentinel custom analytics rule library

Investment

• Mid-market: $200K-$500K
• Enterprise: $500K-$1.5M
• Fortune 500: $1.5M-$3M

Phase 3: Microsoft Entra Identity

Activities

• Microsoft Entra Cloud Sync (or Microsoft Entra Connect)
• Microsoft Entra Conditional Access policy library
• Microsoft Entra ID Protection
• Microsoft Entra Privileged Identity Management
• Google Workspace SAML federation (transitional)

Deliverables

• Microsoft Entra hybrid identity operational
• Microsoft Entra Conditional Access library

Investment

• $100K-$300K (4-8 weeks)

Phase 4: Pilot Migration

Activities

• 100-300 pilot user migration
• Microsoft Outlook + Microsoft Teams + Microsoft OneDrive deployment
• Google Drive → Microsoft OneDrive content migration
• Google Apps Script → Microsoft Power Automate flow conversion
• User acceptance testing

Deliverables

• Pilot users migrated
• Migration playbook validated

Investment

• $50K-$200K (4-8 weeks)

Phase 5: Phased Cohort Migration

Activities

• Phased cohort migration (1,000-2,000 users per month)
• Gmail → Microsoft Exchange Online migration
• Google Drive → Microsoft OneDrive + SharePoint migration
• Google Calendar → Microsoft Outlook calendar migration
• Google Meet → Microsoft Teams migration
• Google Apps Script → Microsoft Power Automate
• Microsoft Sentinel monitoring

Migration Tooling

• Microsoft 365 Migration Manager (Google connector)
• BitTitan MigrationWiz
• Quest On Demand Migration

Deliverables

• All users migrated
• Microsoft 365 license rationalization

Investment

• Mid-market: $200K-$500K (3-6 months)
• Enterprise: $500K-$1.5M (6-12 months)
• Fortune 500: $1.5M-$5M (12-18 months)

Phase 6: Microsoft 365 Copilot Enablement

Activities

• Microsoft Restricted SharePoint Search Day-1
• Microsoft Purview AI Hub configuration
• Microsoft Sentinel custom AI analytics rule library
• Microsoft Compliance Manager AI framework attestation
• 90-180 day permission cleanup
• Microsoft 365 Copilot phased rollout

Deliverables

• Microsoft 365 Copilot operational
• Microsoft Power BI Copilot enabled (F64+ capacity)
• Microsoft Copilot Studio agents (where applicable)

Investment

• Mid-market: $200K-$500K (3-6 months)
• Enterprise: $500K-$1.5M (6-9 months)
• Fortune 500: $1.5M-$5M (9-12 months)

Phase 7: Google Workspace Decommissioning

Activities

• Final cutover validation
• Google Workspace decommissioning
• Microsoft 365 license rationalization
• Microsoft Compliance Manager final attestation

Deliverables

• Google Workspace decommissioned
• Microsoft 365-anchored productivity operational

Investment

• $100K-$300K (4-8 weeks)

Phase 8: 90-Day Hyper-Care

Activities

• Daily monitoring
• Weekly executive briefing
• Microsoft Sentinel SOC monitoring
• Microsoft Defender for Office 365 monitoring
• Microsoft Purview compliance posture review
• Issue triage + resolution

Deliverables

• Stable Microsoft 365 operations
• 90-day post-migration validation

Migration Tooling

Microsoft Native Tools

• Microsoft 365 Migration Manager (Google Workspace connector)
• Microsoft 365 Migration Manager (Box, Dropbox connectors)
• Microsoft Graph API for custom scenarios

Third-Party Tools

• Quest On Demand Migration
• BitTitan MigrationWiz
• AvePoint Cloud Migration
• ShareGate Migration

Industry-Specific Patterns

Healthcare

• Microsoft 365 Commercial with BAA
• HIPAA-aligned Microsoft Purview Restricted-PHI tier
• Microsoft Customer Lockbox
• 7-year Microsoft Purview retention
• HIPAA-aligned Microsoft 365 Copilot

Financial Services

• Microsoft Information Barriers (research-banking-trading)
• Restricted-MNPI sensitivity tier
• SEC Rule 17a-4 retention via Microsoft Purview Records Management
• FINRA Rule 3110 supervised analytics
• Restricted-MNPI Microsoft 365 Copilot

(Detail in Case Study Financial Services Google to M365 Migration 8500 Users)

Government

• Microsoft 365 GCC / GCC High deployment
• FedRAMP-aligned Microsoft 365 Copilot
• CAC/PIV authentication
• DoD STIGs alignment
• Restricted-CUI sensitivity tier

Pharma

• 21 CFR Part 11 audit trail integrity
• Restricted-Clinical sensitivity tier
• CSV documentation
• IND/NDA submission protection

EPC Group Google Workspace → Microsoft 365 Engagement

EPC Group fixed-fee Google Workspace → Microsoft 365 migration:

• Mid-market: $300K-$700K (6-9 months)
• Enterprise: $700K-$2M (9-18 months)
• Fortune 500: $2M-$8M (18-30 months)

Plus optional Microsoft 365 Managed Services: $5K-$60K/month.

Frequently Asked Questions

How long does Google Workspace → Microsoft 365 migration take?

Mid-market: 6-9 months. Enterprise: 9-18 months. Fortune 500: 18-30 months.

What about Microsoft 365 Copilot during migration?

Microsoft 365 Copilot is enabled in Phase 6 after foundation + migration completion. Microsoft Restricted SharePoint Search Day-1 mitigation enables phased rollout.

What about Google Apps Script automation?

Google Apps Script → Microsoft Power Automate flow conversion is part of standard migration. EPC Group includes conversion in fixed-fee engagement.

Who delivers EPC Group migration engagements?

Errin O'Connor (CEO, 4-time Microsoft Press author) leads. Senior Microsoft 365 architects with experience since the original Microsoft 365 era (2014).

Next Steps

Schedule a 30-minute Google Workspace → Microsoft 365 discovery call at /schedule or call (888) 381-9725. Senior architects (not sales) take discovery calls.

Related reading: Microsoft 365 vs Google Workspace Enterprise Comparison, Case Study Financial Services Google to M365 Migration 8500 Users, Microsoft 365 Migration Services Enterprise Record Holder, Microsoft 365 E3 vs E5 Enterprise Comparison, and Hidden Costs of DIY Microsoft 365 Migration Guide.