The impact of COVID-19 on socio-economical activities has changed everyday life. Dental hygienists, who perform aerosol generating procedures, have been strongly affected by changes in routine procedures. This cross-sectional study aimed at carrying out an online survey among dental hygienists in Lombardy. The survey was implemented after the first-wave lockdown focusing on the level of knowledge on COVID-19 and Sars-CoV-2, the virus-related changes in their attitude and working routine, and the socio-economic effects. In this report, we included 313 questionnaires of respondents (259 Females, and 54 Males; age = 33 ± 9 years). A significant percentage of respondents acknowledged the use of “word of mouth” among colleagues (n = 114, 36%) and social networks (n = 113, 36%) to be up to date on COVID-19. About half of respondents correctly identified the main COVID-19 symptoms/signs, just 13% (n = 41) identified the routes of transmission. Three quarters of respondents (n = 234, 75%) were afraid of being infected during the clinical practice, and about half of them would be afraid to treat patients having symptoms attributable to COVID-19. Twenty-one percent (n = 67) of participants also thought about changing job. Air-polishing was identified as the highest risk procedure, and 82% (n = 256) reported that they eliminated its use. Most claimed they never had a swab or a serological test, with two respondents positive to molecular test (0.6%), and 12 positives to serological test (3.8%). More than half of the participants (65%; n = 202) complained the dental hygienist is not protected, despite a loss of earnings due to lockdown between 2,000 and 10,000 euros. This study demonstrated that dental hygienists were emotionally and economically affected by the pandemic, significantly changing their work routine. Anti-epidemic protocols are pivotal to react promptly and to contain the virus in the dental setting.