The 46-year-old has been charged with one count of murder and one count of interfering with a corpse after Mr Morseu was reported missing in November.
Mr Morseu's body has not been found, with police continuing to call for information from the public.
Suspicions were aroused after Mr Morseu had not contacted or been seen by anyone in a number of weeks.
Detective Superintendent Darrin Shadlow said Queensland Police had spoken to more than 120 witnesses.
"We do believe that somebody out there will know something," he told reporters in Mackay on Friday.
"We're still seeking further information in relation to the remains of the missing person.
"We have put a lot of pieces together in this puzzle which has culminated in today's arrest."
In March, police said they believed Mr Morseu had died at his home address in September.
They alleged that the 71-year-old man's body remained in his unit for a period of time, before being moved by someone involved in his death.
Police said the woman resided with the man in a domestic relationship.
She is due to appear before Mackay Magistrates Court later on Friday.
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