Polhemus was born and raised in Arlington, Texas. She attended Arlington High School located in Arlington, Texas. After graduation, Polhemus took her studies to Texas Tech University located in Lubbock, Texas.
After graduating from college, Polhemus started working as a cattle broker and real estate agent in Texas. During this time, she entered her first pageant, Miss Texas USA 1988.
Competing as Miss Bedford USA, Polhemus was named a semifinalist and made it into the Top 5. She ultimately placed as second runner-up to Miss Texas USA 1988, Courtney Gibbs. She also won the Photogenic Award.
After her strong performance, Polhemus decided to return to the Miss Texas USA stage for a second time. She competed in the 1989 Miss Texas USA pageant. This time, as Miss Fort Worth USA, Polhemus was crowned Miss Texas USA 1989.
Polhemus then went on to represent Texas at the 1989 Miss USA pageant. Competing against 50 other contestants, Polhemus had an average preliminary competition score of 9.084, the highest preliminary score of the pageant. On the final night of competition, she was named as one Top 10 semifinalists. After the final competition, Polhemus held an average score of 9.520.
On February 28, 1989, Polhemus was crowned Miss USA 1989 at the Mobile Civic Center Theatre located in Mobile, Alabama. Her win marked the fifth consecutive year Miss Texas USA won the Miss USA crown, a phenomenon known as the “Texas Aces.”
Polhemus then went on to represent the USA at the 1989 Miss Universe pageant held at the Fiesta Americana Condesa Hotel located in Cancún, Mexico. There, she placed fifth in semifinal interview with a score of 8.511, fourth in swimsuit with a score of 8.894 and eighth in evening gown with a score of 8.927. During the final competition, Polhemu was named a semifinalist and cracked the Top 5 where she placed as second runner-up to Miss Universe 1989, Angela Visser, of Holland.
After crowning her successor, Polhemus was a correspondent for ESPN for more than 10 years. She later settled down in Utah where she was the host of Good Things Utah on ABC4 from 2012-2014. She currently works as a producer and host of Utah Works at ABC4 Utah - Good4Utah and a co-host of ABC4’s radio show Good Things Utah.
In 2016, Polhemus became co-owner of Rebel Collagen Skin Care. She has also continued work as a professional model. She and her fitness regime were feature in the November 2013 issue of Shape Magazine. Also, More Magazine listed her as one of the Nation's top models over 35. She has work all over the world including England, Scotland, Iceland, Nova Scotia, Hawaii, Guam, Japan, Korea, Mexico, Canada, New York, Los Angeles, Miami, Chicago and Dallas.
Polhemus would later marry Kirk Jensen. The two are now divorce but have five children, two girls and three boys. She currently resides in South Jordan, Utah.