The decision to put 79-year-old company founder into both roles came at an emergency board meeting late on Monday at the end of a brutal day for Luxottica on the Milan stock exchange.
Investors' uncertainty over the company's leadership structure resulted in its share price plunging 9.2 percent, wiping 1.8 billion euros off its value.
The market was reacting to the announcement on Sunday that Enrico Cavatorta was quitting his role as co-CEO after only 40 days in the job.
Cavatorta, previously chief financial officer at the Milan-based group, had clashed with del Vecchio over the nature of his brief and extent of his powers, according to reports.
Cavatorta had only moved into the CEO role last month following the departure of Andrea Guerra, who left following a similar clash with del Vecchio over the latter's plans to return to a more hands-on role in the company after a decade spent taking a backseat.
Luxottica, owner of the Ray-Ban and Oakley brands, also makess eyewear for designers including Chanel and Giorgio Armani. Its success has made del Vecchio Italy's second richest man.
In a statement, the company said it had accepted Cavatorta's resignation "following disagreements on the current governance structure."
It said another board member, Roger Abravanel, was resigning for the same reason and that the appointment of Masimo Vian as one of the two CEOs del Vecchio wanted to run the company had been suspended.
The company founder had said on Sunday that he wanted Vian to fill both roles on an interim basis pending the appointment of a replacement for Cavatorta, who will remain at the company long enough to prepare quarterly results up to the end of October.
Media reports say the boardroom turmoil reflects divisions over del Vecchio's role and that of his holding company, which owns just over 60 percent of Luxottica shares, against a background of family divisions over succession issues.
Luxottica's share price on Tuesday fell a further 4.73 percent to €35.90 in morning trade in Milan.