By Agence France-Presse
The California-based technology giant said its net income rose eight percent to $5.3 billion, which fell short of Wall Street expectations despite better-than-expected revenue.
Alphabet revenue in the quarter topped $26 billion, up 22 percent from the same period a year earlier.
Its shares slipped more than two percent to $838.29 in after-market trades that followed release of the earnings figures.
"Our growth in the fourth quarter was exceptional," Alphabet chief financial officer Ruth Porat said in the earnings release, crediting mobile search and YouTube with driving the performance.
"We're seeing great momentum in Google's newer investment areas and ongoing strong progress in Other Bets."
For earnings purposes, Alphabet separates operations such as self-driving cars into an "Other Bets" category, which nearly doubled revenue to $262 million in the quarter but still posted a loss of nearly $1.1 billion.
Its main operating unit remains Google and advertising remained the money-making engine for the company, but the number of paid clicks shrank, according to the earnings report.
Under its new structure, Alphabet is seeking to expand beyond its role as a search engine that provides advertising linked to queries. It has grown revenue in mobile search but is moving to further diversify its revenue stream.
Last year, Google took on rivals Apple, Samsung and Amazon in a new push into hardware, launching premium-priced, in-house designed Pixel smartphones and a slew of other devices showcasing artificial intelligence prowess.
Google also revealed its new "home assistant" which aims to compete with Amazon's Alexa-powered devices as a hub for the smart home, and has been working to become the platform for some connected cars.