2021 Belgrade Open

{{about|a one-time tournament|the tennis event held in Belgrade earlier in the year|2021 Serbia Open}}

{{one source|date=August 2021}}

{{TennisEventInfo|2021|Belgrade Open|

| date= 23–29 May

| edition=1st

| category= ATP Tour 250

| draw=28S / 16D

| surface=Clay

| location=Belgrade, Serbia

| venue=Novak Tennis Center

| prize_money = €255,500

| champs={{flagicon|SRB}} Novak Djokovic

| champd={{flagicon|ISR}} Jonathan Erlich / {{flagicon|BLR}} Andrei Vasilevski

| after_year=2024

}}

The 2021 Belgrade Open was a tournament on the 2021 ATP Tour. It was played on outdoor clay courts in Belgrade, Serbia. It was organised with a single-year licence in 2021, and was held at Novak Tennis Center from May 23 to 29, 2021.[https://tennishead.net/world-number-one-novak-djokovic-named-on-entry-list-for-belgrade-2/ World number one Novak Djokovic named on entry list for Belgrade 2]