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.

- 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

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 Prospect: Mentor junior technicians and play a key role in supporting the broader technical team
- Performance Bonus Eligibility
- Paid Time Off & Extended Health Benefits (Medical/Dental/Vision)
- Professional development, training, and certification opportunities

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.

#J-18808-Ljbffr

📌 Senior Systems Administrator (Toronto)
🏢 STACK IT Recruitment
📍 Toronto