The list of 100 undergraduate employers is based on the ratings of 7,000 students of the 2013/14 academic year. Any company that employs more than 15 students a year on placements, internships, vacation schemes and insight programmes is eligible for the awards.
Barclays was also named the top employer in 2012, before slipping to seventh place last year. The 2013 winner, professional services firm Grant Thornton, drops out of the top 10 to 15th place.
Financial services firms dominate the top 10, with Bank of America Merrill Lynch taking second place and Credit Suisse in sixth. Employers are ranked on the amount of responsibility they give students and training and development opportunities, among other criteria.
Barclays head of campus recruiting in EMEA, Jane Clark, said the company strives to create "rewarding work experiences" for interns and students on work placements.
"We are thrilled that the investment we have made in our programmes has once again been recognised within the industry as one of the best," she said. "Being rated top by the students themselves is also a great honour."
RateMyPlacement co-founder Ollie Sidwell said he was pleased to see a "wide range of sectors" in the list, including financial services, law, technology and retail.
"This opens up fantastic opportunities for students, wherever their aspirations lie, and we hope that pitching them all in together will encourage companies to continually raise the bar," he added.
Top 10 undergraduate employers
1 Barclays (7th last year)
2 Bank of America Merrill Lynch (31)
3 EY (5)
4 Morgan Stanley (15)
5 PwC (4)
6 Credit Suisse (17)
7 Pinsent Masons (6)
8 Goldman Sachs (not placed)
9 Nabarro (21)
10 JP Morgan (28)