Job Description

At Critical Mass, people are at the heart of everything we do. As a Contract Senior HR Business Partner (Sr HRBP), you will play a pivotal role in shaping our inclusive, high performing culture across both our Toronto and New York offices. You'll be a trusted advisor to leadership and employees alike, fostering strong cross office relationships, driving key HR initiatives, and championing our commitment to employee growth, engagement, and wellbeing. This is an exciting opportunity for a dynamic HR leader to make a tangible impact-leveraging strategic expertise, business acumen, and a passion for people to propel our organization forward.
Please note that this is a contract position with a requirement to be on location in our Toronto office.
You Will:

• Cultivate strong, authentic partnerships with client leads, creative directors, and employees across Toronto and New York, ensuring each office feels equally supported and connected
• Support the entire employee life cycle-onboarding, development, engagement, performance management, and beyond-with a focus on creating an exceptional, inclusive workplace
• Serve as a strategic thought partner to our General Manager in New York and other senior leaders, providing expert HR guidance and executive coaching while acting as the primary HR point of contact for both locations
• Proactively manage and resolve complex employee relations matters, including investigations and conflict resolution, ensuring fair, consistent, and compliant outcomes
• Lead impactful communications and presentations while supporting organizational change initiatives and drive the successful rollout of HR programs and talent initiatives
• Gather, interpret, and report on HR data and metrics (including turnover, engagement, and talent gaps), providing actionable insights to business leaders and making evidence-based recommendations
• Champion diversity, equity, and inclusion, ensuring our practices reflect our values and supporting a culture where every employee can thrive
• Maintain regular connection with the New York office-including as needed travel-to foster relationships and support onsite needs

You Have:

• 5-7+ years' progressive HR experience in complex, fast paced environments (marketing/agency experience is a plus, but not required)
• Depth in HR disciplines such as talent management, compensation & benefits, employee/labor relations, risk management, change management, and HR technology, with proven ability to interpret and implement HR strategy
• Working knowledge of both US and Canadian employment law-able to make sound, compliant decisions in both regions.
• Exceptional communication, stakeholder management, and executive partnering skills and the ability to influence and coach senior leaders with credibility and confidence
• Strong analytical and critical thinking skills, with the ability to independently assess data, identify trends, and recommend solutions
• Experience leading or contributing to HR projects and supporting organizational change, including talent initiatives and succession planning
• Proficiency in Microsoft Office Suite (especially Excel), documentation, reporting, and virtual collaboration tools
• Agility, empathy, and accountability, with a proven ability to build trust, foster inclusion, and operate effectively within ambiguity and change

This position requires regular travel between Canada and the United States. Candidates must be able to travel freely between both countries.
What We Offer:

• Global maternity and parental leave
• Competitive benefits packages
• Vacation, compassionate leave, sick days, and flex days
• Access to online services for families and new parents
• Diversity and Inclusion Board with 12 affinity groups
• Internal learning and development programs
• Enterprise-wide employee discounts

Our new hires & employees are the future of our organization, and we want to set you up for long-term success. In an effort to do so, we expect our team to work from an office a minimum of 3 days a week.
Critical Mass is an equal opportunity employer.
The Critical Mass Talent Acquisition team will only communicate from email addresses that use the URLs criticalmass.com, omc.com and . We will not use apps such as Facebook Messenger, WhatsApp, or Google Hangouts for communicating with you. We will never ask you to send us money, technology, or anything else to work for our company. If you believe you are the victim of a scam, please review your local government consumer protections guidance and reach out to them directly.
If U.S. based:
If Canada based:
If U.K. based:
If Costa Rica based:

Skills Required