Jacob K. McKenty was born in Douglassville, Pennsylvania. He graduated from Yale College in 1848 and from the law department of that college in 1851. He was admitted to the bar in 1851 and commenced practice in Reading, Pennsylvania. He served as prosecuting attorney of Berks County, Pennsylvania, from 1856 to 1858.
McKenty was elected as a Democrat to the Thirty-sixth Congress to fill the vacancy caused by the death of John Schwartz and served from December 3, 1860, to March 3, 1861. He was not a candidate for reelection in 1860. He was an unsuccessful candidate for nomination in 1862 and 1864. He resumed the practice of his profession in Reading and died in Douglassville in 1866. Interment in St. Gabriel’s Episcopal Church Cemetery.