The message, which included detailed banking information and a request to bury his ashes at a specific site, was found by a friend who was searching through the dead man's phone for clues.
According to the ABC, the Supreme Court in Brisbane has now declared the text message to be a valid will.
"The reference to his house and superannuation and his specification that the applicant was to take her own things indicates he was aware of the nature and extent of his estate, which was relatively small," Justice Susan Brown reportedly said.
The judge made the ruling after the dead man's wife applied to manage her late husband's estate, arguing the text message was not valid as it was never sent.
But Justice Brown found the use of the words "my will" and the detailed references to his superannuation and property indicated he was fully aware of what he was doing.
Justice Brown said she was also aware of evidence indicating he and his wife had an unstable relationship, that he had no relationship with his son, and that they had broken up "just days" before he took his own life.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• LIFELINE: 0800 543 354 (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757