* Uber ( UBER ) to deploy 10,000 Rivian robotaxis starting 2028

* Initial $300 million investment committed; $1.25

billion subject to milestones

* Uber ( UBER ) has an option to buy 40,000 more robotaxis in 2030

By Abhirup Roy and Akash Sriram

SAN FRANCISCO, March 19 (Reuters) - Uber ( UBER ) will

invest up to $1.25 billion in electric vehicle maker Rivian

as part of a deal in which the ride-hailing firm will

start deploying 10,000 fully autonomous R2 SUVs as robotaxis

from 2028, the companies said on Thursday.

San Francisco-based Uber ( UBER ) will make an initial investment of

$300 million, and will fund the remaining amount through 2031,

subject to Rivian meeting certain autonomous milestones, the

companies said.

Interest in driverless taxis has surged in recent months

after years of missed promises, with artificial intelligence and

tech partnerships offering hopes of solving complex traffic

scenarios faster and mitigating high costs.

While Rivian, known for its high-end R1S SUVs and R1T pickup

trucks, has not launched a robotaxi yet, it unveiled its first

custom computer chip for self-driving in December. The company

is also gearing up to roll out its smaller, more affordable R2

SUVs this quarter.

Meanwhile, Alphabet's Waymo, which runs about

2,500 robotaxis in several U.S. cities, has accelerated its

rollouts, while Tesla has launched a small robotaxi

service in Austin, Texas, with CEO Elon Musk promising rapid

expansion this year.

R2 robotaxis will be available exclusively on Uber's ( UBER )

platform, starting with San Francisco and Miami, the companies

said, adding that Uber ( UBER ) has the option to buy up to 40,000 more

beginning in 2030.

"Should all milestones be achieved, the companies will have

deployed thousands of unsupervised Rivian R2 robotaxis across 25

cities in the U.S., Canada, and Europe by the end of 2031," they

said.

Uber ( UBER ) is positioning itself as a marketplace for multiple

robotaxi operators, and has partnered across much of the

autonomous vehicle industry, including with Waymo, Baidu ( BIDU )

and Lucid.

It is also working with Nvidia ( NVDA ) on autonomous

driving, leveraging the chip designer's AI and simulation

platforms to support the development and scaling of robotaxi

systems.