diff --git a/packages/hardhat-core/src/internal/core/errors-list.ts b/packages/hardhat-core/src/internal/core/errors-list.ts
index 15bfe4474a..a77466ad82 100644
--- a/packages/hardhat-core/src/internal/core/errors-list.ts
+++ b/packages/hardhat-core/src/internal/core/errors-list.ts
@@ -201,6 +201,19 @@ Please run: npm install --save-dev typescript`,
 Please run this and try again: \`npm install --save-dev typescript\``,
       shouldBeReported: false,
     },
+    INVALID_PRIVATE_KEY: {
+      number: 15,
+      message: `There's one or more invalid private keys in your config file:
+
+%keys%
+  
+To learn more about Hardhat's configuration, please go to https://hardhat.org/config/`,
+      title: "Invalid private key",
+      description: `You have one or more errors in your config file. 
+      
+Check the error message for details, or go to the [documentation](https://hardhat.org/config/) to learn more.`,
+      shouldBeReported: false,
+    },
   },
   NETWORK: {
     CONFIG_NOT_FOUND: {
diff --git a/packages/hardhat-core/test/internal/core/config/config-validation.ts b/packages/hardhat-core/test/internal/core/config/config-validation.ts
index df1386c3a7..41992bf8cb 100644
--- a/packages/hardhat-core/test/internal/core/config/config-validation.ts
+++ b/packages/hardhat-core/test/internal/core/config/config-validation.ts
@@ -257,6 +257,201 @@ describe("Config validation", function () {
         });
       });
 
+      /**
+       * networkConfig.accounts
+          if string => must === "remote"
+          if object => ~
+          if array => 
+            if network === hardhat =>
+              each => isValidHexString(each.privateKey)
+                && isValidBalance?(each.balance)
+            else (network === http) =>
+              each => isValidHexString(each)
+       */
+
+      /**
+       * This describe block will encompass all private key tests
+       * for both Hardhat and HTTP networks
+       */
+      describe("Private key config", function () {
+        describe("HTTP network accounts", function () {
+          it("Should allow an array of valid private keys", function () {
+            validateConfig({
+              networks: {
+                custom: {
+                  url: "http://localhost",
+                  accounts: [
+                    "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+                    "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
+                    "0xcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
+                  ],
+                },
+              },
+            });
+          });
+
+          it("Should allow valid private keys with missing hex prefix", function () {
+            validateConfig({
+              networks: {
+                custom: {
+                  url: "http://localhost",
+                  accounts: [
+                    "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+                  ],
+                },
+              },
+            });
+          });
+
+          it("Should not allow hex literals", function () {
+            expectHardhatError(
+              () =>
+                validateConfig({
+                  networks: {
+                    custom: {
+                      url: "http://localhost",
+                      accounts: [
+                        0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
+                      ],
+                    },
+                  },
+                }),
+              ERRORS.GENERAL.INVALID_PRIVATE_KEY
+            );
+          });
+
+          it("Should not allow private keys of incorrect length", function () {
+            expectHardhatError(
+              () =>
+                validateConfig({
+                  networks: {
+                    custom: {
+                      url: "http://localhost",
+                      accounts: ["0xaaaa"],
+                    },
+                  },
+                }),
+              ERRORS.GENERAL.INVALID_PRIVATE_KEY
+            );
+
+            expectHardhatError(
+              () =>
+                validateConfig({
+                  networks: {
+                    custom: {
+                      url: "http://localhost",
+                      accounts: [
+                        "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabb",
+                      ],
+                    },
+                  },
+                }),
+              ERRORS.GENERAL.INVALID_PRIVATE_KEY
+            );
+          });
+        });
+
+        describe("Hardhat Network accounts", function () {
+          it("Should allow an array of account objects with valid private keys", function () {
+            validateConfig({
+              networks: {
+                [HARDHAT_NETWORK_NAME]: {
+                  accounts: [
+                    {
+                      balance: "123",
+                      privateKey:
+                        "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+                    },
+                    {
+                      balance: "123",
+                      privateKey:
+                        "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
+                    },
+                    {
+                      balance: "123",
+                      privateKey:
+                        "0xcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
+                    },
+                  ],
+                },
+              },
+            });
+          });
+
+          it("Should allow valid private keys with missing hex prefix", function () {
+            validateConfig({
+              networks: {
+                [HARDHAT_NETWORK_NAME]: {
+                  accounts: [
+                    {
+                      balance: "123",
+                      privateKey:
+                        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+                    },
+                  ],
+                },
+              },
+            });
+          });
+
+          it("Should not allow hex literals", function () {
+            expectHardhatError(
+              () =>
+                validateConfig({
+                  networks: {
+                    [HARDHAT_NETWORK_NAME]: {
+                      accounts: [
+                        {
+                          balance: "123",
+                          privateKey: 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
+                        },
+                      ],
+                    },
+                  },
+                }),
+              ERRORS.GENERAL.INVALID_PRIVATE_KEY
+            );
+          });
+
+          it("Should not allow private keys of incorrect length", function () {
+            expectHardhatError(
+              () =>
+                validateConfig({
+                  networks: {
+                    [HARDHAT_NETWORK_NAME]: {
+                      accounts: [
+                        {
+                          balance: "123",
+                          privateKey: "0xaaaa",
+                        },
+                      ],
+                    },
+                  },
+                }),
+              ERRORS.GENERAL.INVALID_PRIVATE_KEY
+            );
+
+            expectHardhatError(
+              () =>
+                validateConfig({
+                  networks: {
+                    [HARDHAT_NETWORK_NAME]: {
+                      accounts: [
+                        {
+                          balance: "123",
+                          privateKey:
+                            "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbb",
+                        },
+                      ],
+                    },
+                  },
+                }),
+              ERRORS.GENERAL.INVALID_PRIVATE_KEY
+            );
+          });
+        });
+      });
+
       describe("Hardhat Network config", function () {
         it("Should fail with invalid types", function () {
           expectHardhatError(