The photos of the adorable bub quickly went viral, racking up more than 100,000 likes and thousands of retweets – but the reaction was mixed.
While many thought the situation was hilarious, others expressed concern over the "mistake", causing the mum to defend herself online.
"RAFAEL is fine. it's literally like licking a piece of chocolate off ur hand after u tanned he's not downing my whole bottle of tan. I appreciate all ur concern though," she wrote.
She also posted a photo of the bub to "confirm he is okay", adding "don't report me".
Her response came after followers said it was worrying the baby had "ingested harmful chemicals" as a result of the mishap.
Others, however, saw the funny side, calling the fake tan fail "relatable".
Keziah, who is from Derby in the UK, told The Sun she'd tried to "squeeze in" the fake tan application while Raf was asleep – and when she realised what had happened, she "couldn't believe it".
"When I looked down at Raf I just burst out laughing," Keziah said. "I couldn't believe the tan had left his mouth looking like Homer. Raf was asleep so I thought I could squeeze in some tanning time, but he woke up starving mid-tan."
She said it was "the first and definitely last time I feed him with my tan still on. It hadn't actually occurred to me that the tan could transfer onto him. I took a picture and sent it to my girlfriends and they were all laughing as well. Everyone is finding it hilarious and my mum rang me in tears, she found it so funny."