The company says the appeal court affirmed a lower New York State court ruling that LG Electronics did not infringe on Wi-LAN's V-Chip patent.
Wi-LAN says it is "surprised and disappointed'' by the decision and is reviewing its options.
In afternoon trading, Wi-LAN shares where down 40 cents, or 8.16 per cent, to $4.50 on the Toronto Stock Exchange.
V-Chip enabled TVs and digital TV receivers allow owners to block objectionable content.
Wi-LAN licenses the rights to patents in its portfolio and earns money through royalty payments from companies that use the protected technology in their products and services.