The company reported a loss of about $62 million, compared to an $85 million profit in the same quarter a year ago, despite its flagship smartphone line being critically acclaimed by reviewers.
Analysts were expecting a loss of $52 million.
HTC said it generated $1.09 billion in revenue for the January-March quarter, a decline of 22 percent in the year-ago quarter.
The company, which was once third-place behind Apple and Samsung, now has two percent of the global smartphone share, down from more than 11 percent in 2011.
In efforts to stem the financial bleeding, HTC's chief executive Peter Chou offloaded more of his responsibility with the company's chairwoman and co-founder, Cher Wang, late last year.
Earlier this month, the company launched the latest iteration of its flagship phone, the revamped HTC One (M8), which it hopes will resonate with its customer base away from Apple and Samsung.
ZDNet's sister-site CNET gave the smartphone a 4 out of 5 rating — one of the highest ever given for a device — describing it as a "truly great phone all on its own — one worthy of anyone's investment."
Any successes the new flagship phone has will be reported in the company's fiscal second quarter earnings, expected in early May.