"My service as Commissioner has been one of the most rewarding experiences of my public life," Bersin said in a statement. "I am immensely proud of the significant and meaningful achievements we have made on our borders and at our nation's ports of entry over nearly two years."
Homeland Security Secretary Janet Napolitano praised the work Bersin did during his time at the post.
"During his tenure, CBP has taken historic steps to secure our borders while facilitating legal travel and trade," she said in a statement. "Commissioner Bersin has helped set CBP on a path to continuously adapt and seek new and innovative ways of keeping our country – and our communities – safe."
Napolitano said deputy commissioner David Aguilar would fill in as acting commissioner and assistant commissioner Thomas Winkowski would serve as deputy.