Quintin Wiggins, 46, was convicted of one count of misapplication of fiduciary property over $200,000. He faces a sentence ranging from five to 99 years or life in prison.
The jury was set to begin hearing testimony in the trial's sentencing phase shortly after the guilty verdict was announced.
The verdict came after three weeks of testimony and three days of deliberations in the court of state District Judge Brock Thomas.
Harris County prosecutors contended that Wiggins acted criminally when he allowed the use of university funds for such expenditures as furniture, landscaping and a security system for Slade's home.
Defense attorney L. Mickele Daniels told jurors, however, that he may have been negligent, but that he did not intentionally break the law.
He relied on the advice of others for some purchases and did not know about other expenditures, they said.
Wiggins resigned in March last year after the TSU Board of Regents placed him on paid leave in connection with the investigation.
Slade, 55, who was fired in June, is scheduled for trial on Aug. 10 on two counts of misapplication of fiduciary property over $200,000.
She was fired after TSU attorneys concluded that she had failed to follow university policies and state laws while spending more than $260,000.
A criminal investigation concluded that more than $1.9 million was spent during her tenure on such purchases as artwork, club memberships, spa treatments and sports tickets.
Former TSU Vice President Bruce Wilson, 53, charged with one count of misapplication of fiduciary property, is set for trial on Sept. 28.