The 20-year-old singer, who is in the running with bandmate Zayn Malik as the most-tattooed member of One Direction, showed off his new body art as he strolled through the sunny streets of Los Angeles.
The tattoo in question is of a real human heart and was etched onto Harry's left bicep, complete with valves, aortas, ventricles and all. The Worcestershire-born singer already has a design of a cartoon heart just above his new tattoo, which sits next to one of a sailing ship.
"We're always on the road but my heart is at home and I want a ship," Harry has previously explained.
The Midnight Memories singer also admitted that he regretted some of his tattoos, which include one of a padlock, a 99p sign and squiggles.
"I regret this one on my wrist here. I regret this," Harry told We Love Pop. "There are some that my friends have done and some that are just awful."
The mastermind behind the detailed etching is apparently tattoo whizz Liam Sparkes — the same London artist behind Harry's giant butterfly tattoo on his chest.
Since finding fame with One Direction in 2010, Harry has amassed an impressive tattoo collection, including the more noticeable pair of swallows on his chest and an anchor on his left wrist.
While the five-member band scooped two victories at the Brit Awards last week — the Global Success Award and British Video Of The Year for Best Song Ever — Harry was singled out and named Villain of the Year at Wednesday night's NME Awards.
The brunette haired charmer beat out Miley Cyrus, David Cameron and Russian president Vladimir Putin in the category, making it the second time Harry has picked up the award.
The Story of My Life singer skipped the bash and was instead spotted out and about in Los Angeles, where he is currently on holiday with his mum Anne Cox and stepdad Robin Twist.
One Direction at the BRIT Awards
In contrast, Arctic Monkeys singer Alex Turner was crowned Hero of the Year. The 28-year-old also made reference to One Direction at last week's BRIT awards, when Arctic Monkeys scooped the gong for Best British Group.
"There's the 15 quid we put on One Direction to win down the drain," Alex quipped.