Eric Schmidt, chairman of Google's parent company Alphabet Inc, signed the deal with Mayra Arevich Marin, president of state telecommunications company ETECSA. It grants Cubans speedy access to the Google Global Cache network, which stores content from sites like Gmail and YouTube on servers located closer to end users.
"This deal allows ETECSA to use our technology to reduce latency by caching some of our most popular high bandwidth content like YouTube videos at a local level," a Google statement said.
"This may improve reception of cached materials, but not for example email which depends on local bandwidth," a local telecommunications technician said.
Google and ETECSA were not immediately available for comment.
President Barack Obama has made improved internet access a central part of his efforts to normalize relations with Cuba, first announced two years ago.
The Google deal comes as officials in Havana and Washington are working to wrap up pending commercial accords before President Barack Obama leaves office next month.
President-elect Donald Trump has threatened to scrap detente between the Cold War foes unless Cuba makes political and other concessions.
Improved bilateral relations have been accomplished through executive orders circumventing trade embargo laws and can easily be reversed by Trump.
The Obama administration has said it hopes increased commercial links between the two countries will make it difficult for future administrations to undo the recent warming in U.S.-Cuba relations.