Shares of Fitbit ended the day up more than 25 percent Thursday after the company beat estimates on earnings and revenue.

San Francisco-based Fitbit surpassed expectations for a 1-cent loss per share in the third quarter, reporting earnings of 4 cents per share. The wearables company beat on revenue as well, reporting $394 million for the quarter.

Also after the bell on Wednesday, Fitbit said its smartwatch sales grew significantly over the third quarter, making up 49 percent of total revenue, compared to under 10 percent less than a year ago.

"Fourteen months ago we had zero percent share" in smartwatches, Fitbit CEO James Park said on "Squawk Alley" on Thursday. "Now we're No. 2, beating the likes of Samsung."

The company expects unit shipments to grow year over year, Park said.

Fitbit delivered mixed guidance for the fourth quarter, forecasting over 7 cents per share, beating analyst estimates of 6 cents. It sees lower-than-expected revenue of $560 million.

"We're actually expecting to post profitability again in Q4, just like we did in Q3," Park said. "Again, there's a lot of positive momentum that we have going into the holiday season."

— CNBC's Tyler Clifford and Carmin Chappell contributed to this report.