The Mark Yeo is a short river in Somerset. It rises near Mark on the Somerset Levels and flows north for about 4 miles under the M5 motorway to join the River Axe near Loxton. It provided a link between the Axe and the River Brue, and may have been canalised in the 13th and 14th centuries.
The Mark Yeo is one of several rivers called the River Yeo in Somerset and Devon, and is known as the Mark Yeo to avoid confusion with the others. The name Yeo is from the Old English word ea, meaning simply "river".
The river flows under the A38 road at Rooks Bridge. In the 5th and 6th Centuries the Mark-Yeo acted as a route from the small port of Rackley on the river Axe across the marshes to Glastonbury.  Excavations just north of York Farm in a field called 'Scott's wharf' at Rooks Bridge uncovered 14th or 15th century pottery and worked stones, which represent the site of a wharf at a site where the Mark Yeo used to join the old river Axe before it was diverted.
In 2008 an oil spill threatened some of the birds and other wildlife on the river.
- "Mark Yeo River". Somerset Rivers. http://somersetrivers.org/index.php/Search/themes/mediashare/index.php?module=Content&func=view&pid=52. Retrieved 31 March 2010.
- "Pilrow Cut". Somerset Historic Environment Record. Somerset County Council. http://webapp1.somerset.gov.uk/her/details.asp?prn=28600. Retrieved 31 March 2010.
- "About us". Rooksbridge and East Brent. http://www.rooksbridge.org.uk/About%20us.htm. Retrieved 31 March 2010.
- "Mediæval wharf, N of York Farm, East Brent". Somerset Historic Environment Record. Somerset County Council. http://webapp1.somerset.gov.uk/her/details.asp?prn=10051. Retrieved 31 March 2010.
- "Environment Agency appeals for help after oil spill near Burnham". Burnham on Sea .com. http://www.burnham-on-sea.com/news/2008/oil-spill-appeal-25-02-08.shtml. Retrieved 31 March 2010.