In a survey of about 1,000 workers at middle management level and higher, 38% quoted "professional anxiety" as a limiting factor in career progression to C-suite positions.
The uncertainty is felt among both men and women, with 37% of male workers saying they lacked confidence, compared to 39% of women.
The level of anxiety is more pronounced in smaller companies. Almost half (43%) of managers in businesses with fewer than 49 employees cited "professional insecurity" as holding back their career progression, compared to 33% in companies with between 50 and 249 employees. The figure for employers with more than 250 workers rises slightly to 36%.
Nearly a quarter (22%) of respondents said there are no formal career progression structures in place at work. In companies with fewer than 250 employees this figure was 35%, compared to just 13% for larger companies.
Nicola Linkleter, managing director of Badenoch & Clark, told HR magazine employees are increasingly having to "lean in" if they have aspirations of reaching the boardroom.
"There is an immense pressure on employees to forge their own path," she said. "With some organisations having few formal structures in place, many candidates are feeling the pressure."
She added that "supportive mechanisms" are key for retaining and progressing top talent.
"With little signposting and advice provided by the employer, doubts about career development are stopping top talent from getting ahead," she said. "This is a loss for both the candidate and the company."