Principal Machine Learning Scientist

Our client is a leading product-led technology company building next-generation AI-powered platforms at scale, serving millions of users globally. They are heavily investing in AI, Search, and Personalization.

We are hiring a Principal Machine Learning Scientist to lead their core AI initiatives.

Role Overview We are looking for a visionary Principal ML Scientist with deep expertise in Recommendation Systems, User Search, and AI Agentic Model Development. This is a high-impact, individual-contributor + tech leadership role where you will architect and own the AI strategy for discovery, search relevance, and autonomous agent experiences.

You will work directly with Product, Engineering, and Research leadership to solve ambiguous, large-scale problems.

What You Will Do 1. Recommendations & Personalization

Design, build and scale state-of-the-art recommendation and ranking systems (candidate generation, ranking, re-ranking)

Drive personalization strategies to improve user engagement, retention, and conversion

Work on large-scale user behavior modeling, collaborative filtering, deep learning based recommenders

2. AI Agentic Systems

Lead the design and development of Agentic AI models - autonomous agents capable of reasoning, planning, tool-use, and multi-step execution

Build LLM-based agents, orchestration frameworks, memory, and evaluation systems for real-world applications

Research and implement RAG, function calling, and agentic workflows at production scale

3. User Search & Discovery

Own and improve the end-to-end User Search stack - query understanding, retrieval, semantic search, ranking and relevance

Apply LLMs, embeddings, and vector search to build next-gen intelligent search experiences

Define and track search quality metrics and drive continuous improvements

4. Leadership & Impact

Act as a Principal Scientist and thought leader - mentor senior scientists and engineers

Drive research to production - from prototyping to deployment on large-scale distributed systems

Partner with stakeholders to translate business problems into ML solutions

What You Bring PhD / Masters in Computer Science, AI/ML, Statistics or related field. PhD preferred.

10+ years of experience in Machine Learning, with at least 4+ years in a Principal / Staff Scientist role.

Proven track record in building and shipping large-scale Recommendation Systems.

Hands-on expertise in AI Agentic Model Development - LLM Agents, LangGraph / AutoGen / CrewAI or similar frameworks, planning & reasoning.

Strong expertise in User Search - Learning to Rank (LTR), semantic search, embeddings, vector databases (Pinecone, Weaviate, Milvus, FAISS).

Expert in Python, PyTorch / TensorFlow, and ML on big data stack (Spark, etc.)

Deep knowledge of LLMs, Transformers, RAG, Fine-tuning, RLHF / DPO.

Publications in top-tier conferences (NeurIPS, ICML, KDD, SIGIR, RecSys, is a strong plus.

Bonus Points Experience with multi-modal search and recommendations

Experience building evaluation frameworks for Agentic AI

Experience in a B2C product company at scale

Why Join Principal-level ownership and influence on a product used by millions

Opportunity to build Agentic AI from 0-to-1, not just incremental improvements

Top-tier compensation, benefits, and research culture

Note: We are hiring at various budgets and levels depending on experience - from Staff ML Scientist to Principal ML Scientist - compensation will be aligned accordingly