The unidentified victim was found around noon in the Colorado River between the communities of Highland Haven and Kingsland, said Burnett County sheriff's office captain Tom Dillard.
Heavy rains caused a river in the central Texas region to become almost record-breaking in one day, causing collapse of the bridge, flooded homes and evacuation.
Video by Darlene Walthall also showed the river washing across the span before collapsing.
The Llano County Emergency Management Office ordered people live within a quarter mile of the river to evacuate Tuesday morning.
The Llano River meets the Colorado River in Kingsland. Houses near the Colorado were flooded, resident Terri Kleen said. The video she posted on Instagram showed that water rose to the top of the jetty constructions.
Law enforcement officials helped people from flooded areas, she said.
Gov. Greg Abbot issued a state disaster declaration on Tuesday for 18 counties affected by the floods, including the district of Llano.
"Texas is taking immediate action to respond to the threat of recent storms and floods across the state," the governor said in a statement.
In nearby Marble Falls, Dale Heath recorded the video of a car stuck in a rushing water from a swollen Backbone Creek, a tributary of the Colorado River.
The flooded communities are about a 90-minute drive northwest of Austin.
The Llano River Crest in Llano was just below the record high of 41.5 feet in June 1935.
The river is expected to retire by Tuesday afternoon, but should remain in the main flood phase – over 23 feet – though Wednesday morning ,
CNN's Brandon Miller, David Williams and Gianluca Mezzofiore contributed to this report.