The $100M+ AI Startup Boom in 2025: Every Major U.S. Funding Round

Introduction

2024 was a monumental year for artificial intelligence (AI) funding in the U.S., with 49 startups raising $100M+ and seven of them securing billion-dollar rounds. Investors clearly signaled their appetite for AI innovation—and 2025 is proving even bigger.

By Q3 2025, dozens of U.S. AI startups have already joined the “$100M Club”, with multiple billion-dollar raises, repeat mega-rounds, and record-breaking valuations. This article organizes all those rounds—by industry, category, and month—to highlight the biggest trends shaping the AI ecosystem today.

The surge in funding is not just about capital—it’s about how startups are racing to build scalable AI products. Recently, we covered how Google Gemini Turbo is redefining AI writing in 2025, showing how quickly the ecosystem is evolving from research labs to billion-dollar companies.

1. Mega-Rounds at a Glance

Here are the highlights of 2025 so far:

• OpenAI’s $40B round in March—largest private raise in tech history.
• Anthropic’s $3.5B raise in March, valuing it at $61.5B.
• Thinking Machines Lab shocked the industry with a $2B seed round in July.
• Multiple repeat mega-rounds: Harvey, Abridge, and others closed more than one $300M+ round this year.

2. Industry Breakdown

Instead of a simple month-by-month list, let’s organize the companies into themed categories:

🏥 Healthcare AI

Healthcare remains the hottest AI vertical in 2025.

• EliseAI ($250M, Aug) – automating healthcare + housing.
• Ambience Healthcare ($243M, Jul) – building a healthcare operating system.
• OpenEvidence ($210M, Jul) – clinician-focused AI search.
• Abridge ($300M, Jun; $250M, Feb) – medical transcription AI, now valued $5.3B.
• Tennr ($101M, Jun) – AI for healthcare automation.
• Hippocratic AI ($141M, Jan) – large language models for healthcare.
• Insilico Medicine ($110M, Mar) – AI-powered drug discovery.

Takeaway: Investors see AI not just as an efficiency tool but as a core operating system for healthcare.

⚖️ Legal & Compliance AI

AI is rapidly transforming the legal sector:

• Harvey ($300M, Jun; $300M, Feb) – AI legal tools, valuation now $5B.
• Eudia ($105M, Feb) – AI legal tech startup.

Takeaway: Legal AI is no longer niche—it’s becoming a mainstream investment theme.

💻 Infrastructure & Research Labs

The battle to build AI foundations is driving billion-dollar rounds:

• OpenAI ($40B, Mar) – valued at $300B.
• Anthropic ($3.5B, Mar) – $61.5B valuation.
• Thinking Machines Lab ($2B, Jul) – early-stage mega bet.
• Anysphere ($900M, Jun) – coding assistant Cursor.
• Reka AI ($110M, Jul) – research lab.
• Decart ($100M, Aug) – AI research, valued $3.1B.
• Reflection.Ai ($130M, Mar) – autonomous intelligence.
• LMArena ($100M, May) – community benchmarking tool.
• TensorWave ($100M, May) – infrastructure with AMD GPU clusters.
• Lambda ($480M, Feb) – GPU infrastructure.
• Celestial AI ($250M, Mar) – chip + photonics.
• EnCharge AI ($100M, Feb) – AI hardware.

Takeaway: Billions are being poured into compute, infrastructure, and foundational models, setting the stage for the next OpenAI-style giants.

🎨 Generative Media & Productivity AI

Startups pushing creativity and enterprise productivity:

• Fal ($125M, Jul) – generative media platform.
• Runway ($308M, Apr) – media production models.
• Snorkel AI ($100M, May) – data labeling.
• Turing ($111M, Mar) – coding startup.
• Glean ($150M, Jun) – enterprise search, $7.25B valuation.
• SandboxAQ ($450M, Apr) – AI for modeling & simulation.

Takeaway: Generative AI is moving from content creation to enterprise utilities.

🔊 Voice, Search & Consumer AI

• ElevenLabs ($180M, Jan) – synthetic voices.
• OpenEvidence ($210M, Jul) – clinician search.
• Together AI ($305M, Feb) – open-source AI models.

Takeaway: Voice + search are proving to be sticky use cases with direct B2C and B2B adoption.

🛡️ Defense & Specialized AI

• Shield AI ($240M, Mar) – defense AI, $5.3B valuation.
• Lila Sciences ($200M, Mar) – “science superintelligence.”

Takeaway: Expect national security and science-driven AI startups to attract more government-backed funding.

3. Month-by-Month Recap (Quick Timeline)

• Jan: ElevenLabs, Hippocratic AI.
• Feb: Harvey, Eudia, EnCharge, Lambda, Abridge, Together AI.
• Mar: Anthropic, OpenAI, Shield AI, Reflection.Ai, Celestial AI, Turing, Insilico, Nexthop, Lila Sciences.
• Apr: SandboxAQ, Runway.
• May: Snorkel AI, LMArena, TensorWave.
• Jun: Anysphere, Glean, Tennr, Harvey (again), Abridge (again).
• Jul: Fal, Ambience Healthcare, Reka AI, Thinking Machines, OpenEvidence, Harmonic.
• Aug: EliseAI, Decart.

4. Key Trends to Watch

1. Repeat Mega-Rounds – Startups like Harvey & Abridge raising multiple $300M rounds in the same year.
2. Billion-Dollar Seeds – Thinking Machines’ $2B “seed” is unprecedented.
3. Healthcare AI Surge – Healthcare leads all categories, attracting cross-stage funding.
4. Infrastructure Wars – From GPUs (TensorWave, Lambda) to chips (Celestial, EnCharge), compute startups are VC magnets.
5. Enterprise Adoption – Companies like Glean & Harvey show strong enterprise traction.

FAQ

Q1. Why are so many AI startups raising $100M+ in 2025?
AI adoption across industries like healthcare, legal, and enterprise software is exploding. Investors see massive market potential, so they are pouring capital into companies building foundational models, infrastructure, and specialized AI tools.

Q2. Which is the biggest AI funding round of 2025 so far?
The largest funding round in 2025 is OpenAI’s record-breaking $40 billion raise, which pushed its valuation to $300 billion. Anthropic also raised a massive $3.5 billion, making them one of the top-funded startups this year.

Q3. Which industries are attracting the most AI funding in 2025?
The biggest funding flows are going into:

• Healthcare AI (Abridge, Ambience Healthcare, Hippocratic AI)
• AI Infrastructure & Cloud (Lambda, Celestial AI, TensorWave)
• Generative AI for media & productivity (Runway, Fal, ElevenLabs)
• Legal & enterprise AI (Harvey, Eudia, Glean)

Q4. What does “Series A, B, C, D” mean in startup funding?

• Seed/Series A: Early-stage investment to build product & team.
• Series B/C: Growth capital to scale operations & customer base.
• Series D/E+: Late-stage, usually preparing for IPO or acquisition.
  The higher the series, the more mature and valuable the company typically is.

Q5. Will AI startup funding slow down in 2026?
While funding may stabilize, the demand for AI across industries suggests continued strong investment. However, only startups with clear business models and real-world applications are likely to keep raising mega-rounds.

Conclusion

The U.S. AI ecosystem in 2025 is rewriting the rules of venture capital. Billion-dollar rounds are no longer rare, healthcare is the hottest AI vertical, and infrastructure plays are capturing global investor attention.

If 2024 was the breakout year, 2025 looks like the year of scale—where AI startups aren’t just raising money, they’re reshaping entire industries.