The activity was arranged by the club's Fijian back-row Netani Talei to raise awareness for Walk On Walk Strong (WOWS), a charity in his homeland that supports disadvantaged children with life-threatening illnesses.
The big number eight began his work for WOWS following an emotional visit to a children's hospital while on international duty earlier in the summer, which inspired him to help raise the profile of the charity outside of the South Sea Islands.
Talei said: "Seeing the kids when we visited the hospital made me realise I had to get involved as many of the children's parents can't afford the treatment they need. These kids wouldn't get the right help if it wasn't for WOWS.
"Today's head shaving was obviously a good way for Nel to get to know everyone in the squad but, much more than that, it's a great gesture by all the guys taking part to help raise awareness for the charity."
Nel, who arrived a fortnight ago from Super Rugby side Free State Cheetahs, agreed: "Today was a bit of an early initiation and ice-breaker for me and my new teammates and also a good way to raise awareness for a great cause.
"I'm sure he [Talei] got me involved as a fun way of getting to know everyone in the squad and for that I'm really grateful. All the guys have been brilliant since I arrived, and I've been made to feel really welcome.
"The weather will take me some time to get used to because it's a lot colder than back home, especially for summer, but it's a great city. I've only been here a week but my first impressions are good and I'm really looking forward to the season ahead.
"Hopefully we can build on what the guys did last season in the Heineken Cup and make a big impression on the RaboDirect PRO12 - it would be great to be playing in the knockout stages in my first season.
"On a personal note, it's about learning the style the coaches want us to play and making an impact whenever I'm called upon. It's going to be a very exciting campaign and I can't wait to get started."
Nel is in line to make his first Edinburgh Rugby appearance at Kingston Park, when the club takes on Newcastle Falcons on Friday 17 August (kick-off 7.45pm), before a first home outing against Northampton Saints the following Friday (24 August, kick-off 7.30pm) at Murrayfield Stadium.
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland