The Taiwan-based company, known as Hon Hai Precision Industry Co. lists Apple as its largest customer.
It said in the quarter, net profit fell 39% to US$695.5mln ($21.0bn New Taiwan dollars), sharply down from the NT$35.6bn consensus forecast by analysts.
Its revenue during the same quarter remained flat at NT$1.1trln year-on-year.
Foxconn, which is well-known for assembling Apple's iPhones in China, has been bearing the brunt of the iPhone X production issues. Apple launched the sales of iPhone X on November 3, six weeks after the iPhone 8 and 8 Plus.