The Seventeen Going Under singer said in the post: "It seems completely hypocritical of me to advocate discussion on mental health and write songs about it if I don't take the time to look after my own mental health."
The hitmaker added, "It's impossible to do this work on myself while on the road, and it's exhausting feigning happiness and wellness for the sake of business.
"My friends and colleagues have been worried about me for a while and it's not going to get better unless I take the time to do so."
The singer told fans he is "eternally overwhelmed" by their love and support and hates to let them down. However, he said he has no choice as the "state of my wellbeing is starting to affect everything I do."
The star went on to say that despite cancelling his US and UK tour dates he is "super excited" for his Australian tour dates in late November.
Fender is due to perform in Melbourne on November 18, Adelaide on November 19 and Brisbane on November 24 with tickets still available for the first two shows.
The Getting Started singer ended the post with "Me and the boys are burnt out and we need this time,"
Adding, "Thank you for always sticking by us."
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633 or text 234 (available 24/7)
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (12pm to 11pm)
• Depression helpline: 0800 111 757 or text 4202 (available 24/7)
• Anxiety helpline: 0800 269 4389 (0800 ANXIETY) (available 24/7)
• Rainbow Youth: (09) 376 4155If it is an emergency and you feel like you or someone else is at risk, call 111.