Senior systems administrator Jobs in Toronto, ON

Are you a hands-on Systems Administrator who enjoys solving complex infrastructure problems and working across a variety of client environments?

We’re looking for a Senior Systems Administrator to join a growing managed IT services provider supporting clients across the Greater Toronto Area. This is a hands-on role with a strong focus on virtualization, Microsoft 365, Azure, and networking.

The ideal candidate has strong infrastructure experience, is comfortable working directly with clients, and can take ownership of technical issues from troubleshooting through to resolution.

📍 Work Type:

• Fully Onsite - 5 days a week in-office or visiting client sites; on-call and after hours support when required
• Location: Toronto, ON
• Work Type: This is a newly created position

Requirements

🎯 What You’ll Do:

• Manage and troubleshoot virtualized infrastructure, including Nutanix HCI environments
• Administer and support Microsoft 365 environments, including Exchange Online, SharePoint, Teams, OneDrive, and user/license management
• Support Azure and Entra ID environments, including hybrid identity and cloud infrastructure
• Configure, maintain, and troubleshoot network infrastructure, including LAN/WAN, VLANs, firewalls, VPNs, and Wi-Fi
• Serve as a senior escalation point for complex technical issues and Level 1/2 tickets
• Support server, endpoint, operating system, and infrastructure-related issues across client environments
• Lead and support infrastructure projects, including migrations, upgrades, and implementations
• Monitor system health and proactively identify and resolve potential issues
• Maintain accurate technical documentation, network diagrams, and infrastructure standards
• Work directly with clients and vendors to resolve technical issues and deliver solutions
• Provide technical guidance and mentorship to junior technicians
• Apply security best practices across client systems and infrastructure

⭐ What We’re Looking For:

• 5+ years of experience in Systems Administration, Infrastructure Engineering, or a similar role
• Experience working within an MSP, managed services, or multi-client environment
• Hands-on experience administering Nutanix HCI, including cluster management and AHV/VM administration
• Strong experience administering Microsoft 365, including Exchange Online, SharePoint, Teams, and OneDrive
• Experience with Azure and Microsoft Entra ID, including hybrid environments
• Solid understanding of networking, including LAN/WAN, VLANs, firewalls, VPNs, and routing
• Experience with Windows Server and on-premises Active Directory
• Experience with RMM and PSA platforms; HaloPSA and NinjaOne are an asset
• Strong troubleshooting and problem-solving skills
• Experience mentoring, coaching, or providing technical direction to junior technicians
• Strong client-facing communication skills and the ability to work with both technical and non-technical stakeholders
• Strong organizational skills and the ability to manage multiple client environments and competing priorities

Nice to Have

• Cybersecurity experience from a systems/infrastructure administration perspective
• Experience with SentinelOne, Microsoft Defender, or other EDR/MDR platforms
• FortiGate or other firewall experience
• Microsoft 365 security experience, including Conditional Access, MFA, Intune, and DLP
• Experience with infrastructure migrations to Azure/Microsoft 365
• ITIL Foundation or working knowledge of ITIL practices
• Experience supporting law firms or professional services organizations
• Experience with operational technology (OT), building automation, or commercial property environments
• Nutanix or Microsoft certifications

🔥 What Makes This Role Exciting?

• Technical Variety: Work across virtualization, cloud, Microsoft 365, networking, and infrastructure
• Client Exposure: Work directly with a diverse client base and become a trusted technical resource
• Hands-On Environment: Take ownership of real infrastructure challenges and projects
• Technical Growth: Continue developing your expertise across modern infrastructure and cloud technologies
• Leadership Opportunity: Mentor junior technicians and play a key role in supporting the broader technical team

Benefits

• Base Salary: $90,000 - $120,000
• Performance Bonus Eligibility
• Paid Time Off & Extended Health Benefits (Medical/Dental/Vision)
• Professional development, training, and certification opportunities

📩 Ready to Elevate Your Career? Apply Now!

At STACK IT Recruitment, we connect top talent with standout opportunities. If you meet at least 70% of the qualifications, we encourage you to apply, we’d love to chat!

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✨ We’re committed to diversity and inclusion. Need accommodation during the hiring process? Let us know, we’re here to support you!

AI Use Disclosure:

STACK IT uses AI-enhanced tools to support initial candidate screening and interview note analysis. All assessments and hiring decisions remain human-led.