The funding boom for US AI startups shows no signs of slowing in 2025. Just a few months into the year, investors have already poured hundreds of millions into AI-focused companies across sectors, building on the record-breaking momentum seen in 2024.
Last year, 49 US AI startups raised funding rounds worth $100 million or more. This year is off to an even faster start, with more nine-figure rounds already closed in Q1 2025 than during the same period last year. From generative AI to infrastructure and healthcare, investors continue to bet big on the next generation of artificial intelligence pioneers.
Here are the US AI startups that have raised $100 million or more so far in 2025:
April: High-Value Rounds in AI Infrastructure and Media
April kicked off strong with SandboxAQ, an advanced AI model company, securing a $450 million Series E on April 4. The round valued the US AI startup at $5.7 billion and included participation from Nvidia, Google, and Bridgewater’s Ray Dalio.
On April 3, generative media platform Runway closed a $308 million Series D round led by General Atlantic, bringing its valuation to $3 billion. Other investors included SoftBank, Nvidia, and Fidelity.
March: Record-Breaking Investment in US AI Startups
March was packed with capital-heavy deals, led by OpenAI, which closed a $40 billion round on March 31. The deal valued the company at $300 billion, making it the largest round ever raised by a US AI startup. SoftBank led the round, alongside Microsoft, Thrive Capital, and Coatue.
Infrastructure-focused Nexthop AI raised $110 million in a Series A led by Lightspeed on March 25, joined by Kleiner Perkins and Battery Ventures.
Generative biotech platform Insilico Medicine, based in Cambridge, brought in $110 million in a Series E, co-led by Value Partners and Pudong Chuangtou, valuing the US AI startup at $1 billion.
Optical computing company Celestial AI landed a $250 million Series C on March 11, led by Fidelity. The company, valued at $2.5 billion, is building infrastructure for next-gen data centers.
Also in March, Lila Sciences came out of stealth with a $200 million seed round. The startup aims to build a science-oriented superintelligence, with backing from Flagship Pioneering and General Catalyst.
Brooklyn-based Reflection.Ai, focused on autonomous systems, raised $130 million in Series A funding. The US AI startup is only one year old and was backed by Lightspeed and CRV.
Developer platform Turing, which helps AI models scale, closed a $111 million Series E round on March 7, bringing its valuation to $2.2 billion.
Defense tech leader Shield AI brought in $240 million in Series F funding on March 6, pushing its valuation to $5.3 billion. The US AI startup builds AI pilots for military aircraft and was backed by L3Harris and Andreessen Horowitz.
One of the largest raises in March came from Anthropic, which closed a $3.5 billion Series E round led by Lightspeed. The round valued the US AI startup at $61.5 billion and included Menlo Ventures, Salesforce, and General Catalyst.
February: Healthcare, Hardware, and Legal Tech
In February, open-source model builder Together AI raised a $305 million Series B led by Prosperity7 and General Catalyst. The round valued the company at $3.3 billion.
Hardware specialist Lambda secured a $480 million Series D on February 19, backed by Nvidia, SGW, and ARK Invest. The round valued the startup at $2.5 billion.
Healthcare transcription platform Abridge raised $250 million in a Series D round, co-led by IVP and Elad Gil, valuing the AI startup at $2.75 billion.
Legal AI platform Eudia raised $105 million in a Series A round led by General Catalyst on February 13. The startup is redefining legal workflow automation.
That same day, EnCharge AI, based in Santa Clara, raised $100 million for its next-gen AI chips. Tiger Global and Samsung Ventures joined the round.
Legal tech leader Harvey closed a $300 million Series D on February 12, led by Sequoia. The round valued the US AI startup at $3 billion, with OpenAI’s Startup Fund also participating.
January: Strong Start for Voice and Health AI
The year began with ElevenLabs, a synthetic voice US AI startup, raising $180 million in Series C funding co-led by Andreessen Horowitz and ICONIQ Growth. The round pushed its valuation beyond $3 billion.
Another major January deal came from Hippocratic AI, a healthcare-focused language model company. It raised $141 million in Series B funding on January 9, valuing the startup at $1.6 billion.
What These Megarounds Signal for US AI Startups in 2025
From foundational models to niche industry tools, US AI startups are proving they can attract capital at an unprecedented pace. The first quarter alone saw billions in funding committed to just 19 companies — and the year is far from over.
With venture capital continuing to flow into artificial intelligence, it’s clear that the next wave of innovation will be shaped by how these startups scale. As enterprise demand grows and regulatory frameworks evolve, expect even more megarounds in the months ahead.
