2021年に発見された太陽系外惑星の一覧 （2021ねんにはっけんされたたいようけいがいわくせいのいちらん）では、2021年 に発見された太陽系外惑星 について述べる。
ケンタウルス座α星Ab（C1と示されている）の画像 YSES 2bの画像 TOI-175系の惑星 2021年にはTESS 、次世代トランジットサーベイ （NGTS）、Optical Gravitational Lensing Experiment （OGLE）、韓国マイクロレンジング望遠鏡ネットワーク （KMTNet）等によって太陽系外惑星が発見されている。また、ケプラー宇宙望遠鏡 の惑星候補の確認によっても多数の太陽系外惑星が発見されている。
惑星の質量について、地球質量
M
⊕
{\displaystyle M_{\oplus }}
M
J
=
M
⊕
317.83
{\displaystyle M_{J}={\frac {M_{\oplus }}{317.83}}}
地球半径
R
⊕
{\displaystyle R_{\oplus }}
R
J
=
R
⊕
11.21
{\displaystyle R_{J}={\frac {R_{\oplus }}{11.21}}}
木星質量
M
J
{\displaystyle M_{J}}
木星半径
R
J
{\displaystyle R_{J}}
光年 （
l
y
{\displaystyle ly}
p
c
=
l
y
3.26
{\displaystyle pc={\frac {ly}{3.26}}}
パーセク （
p
c
{\displaystyle pc}
褐色矮星 またはその可能性が高いもの（木星質量の13倍を目安とする）は記載していない。グリーゼ近傍恒星カタログ での表記はすべて「GJ」にしている。（例: グリーゼ581 → GJ 581）発見方法の欄にある「RV」はドップラー分光法 、「T」はトランジット法 、「I」は直接観測法 、「M」は重力マイクロレンズ法 、「TTV」はTTV法 、「A」はアストロメトリ法 、「TM」は各種タイミング法 、「DK」はDisk Kinematics法、「OBM」は軌道輝度変調法を表し、これら以外の発見方法は「O」で表す。
惑星の欄は予想される形態により以下の4色によって表されている。
太陽系外衛星 は記載していない。太陽系外衛星は太陽系外衛星の一覧 を参照。
2021年に太陽系外惑星は540個発見され、その発見が確定している。
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