The black-and-white snap features both singers handcuffed together, with both showing off irritated faces. Lavigne wore a black leather jacket paired with matching leather pants and a crop top, while also rocking her brand-new long bob. Yungblud posed in black leather pants, suspenders and a white T-shirt, while accessorizing with a safety pin earring and a chain necklace.
"'I'm a Mess' with [Yungblud] out Thursday, Nov. 3," the 38-year-old told her nearly 12 million followers in her caption.
Fans met Lavigne's announcement with praise for her fresh new look and excitement over her upcoming song.
"Hair is a slay," one fan commented, while another added, "Your hair looks so good. I'm obsessed."
"Oh my God, Avril. This hair is amazing!" someone else wrote.
One person penned, "Wow, you look killer, Avril! Cannot wait for this new song!"
"Loving the new hairstyle," another chimed in.
"Love your short hair!" a fan shared, while another commented, "Your hair, omg! A new era is coming!"
"This haircut is so shocking! You've always had long hair!" someone wrote. "I love the new look though. It suits you, queen!"
Earlier this week, the Canadian songstress shared a video on Instagram of Yungblud taking a pair of scissors to her long blonde locks, while she sat on a toilet, nervously repeating, "I need a beer!"
"Are you ready? Are you nervous?" the 25-year-old "Tissues" singer asked before lopping off several inches of Lavigne's hair. "I'm going to cut it into a bob for you."
Lavigne's fiancé, Mod Sun, gave his stamp of approval, commenting, "Haircut looks great! You did well, [Yungblud]. New song, maybe?"
Fans were also quick to show their support in the comments.
"I wanna see short-haired Avril," one Instagram user sounded off.
"It looks amazing. omg!" added another.
"Omg! I don't think we've ever seen you with short hair," a fan penned, alongside a heart and flame emoji.