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 Opportunity: 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)

Career 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.

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